Are we wrong for not inviting my MIL and SIL to our micro wedding ceremony?

You really should have included this in your first post, instead of as an update. I think more PPs would agree with the decisions you and DH have decided on.
Both his parents sound awful.

@JanineR I'm sorry, I just don't think your later explanations are quite what happened. You gave a very different impression in your first few posts, and it is hard to understand that as you could only have two witnesses, you didn't each choose to have your own Mums' and either leave it like that, or have the Aunt as well because you are both close to her.

If signing the paperwork at the Registry office doesn't seem important to either of you, then why not live together until you can have the Roman Catholic Wedding that is obviously so important to - which is fine in case I sound disapproving?

However, did your DFiancé want to join the RC Church before he met you, or is it a case of if he wants to marry you then he has to be baptised into your faith, and presumably he has had to agree to your children being brought up in that faith, which will presumably also mean that any Christenings, confirmations, etc. will be led by your, and your Mum's beliefs? As I said before, all of that is fine because your DFiancé is am adult, so is presumably agreeable to all of those conditions.

But what it does probably show is that you have already got your own way in a lot of things to do with this Wedding, and that it would therefore be kinder and more generous of you to let your DF have more priority over the guest list at the Civil Ceremony, as that will presumably be of more importance to his family members, than to your DM and DSis? I also expect that your family members will give much more importance to the religious ceremony, than the civil one. Of course I am making assumptions here, and I give you my apologies if I have made an error in my assumptions.

Unless things have changed, I think that for legal reasons you have to have a civil service as well, when you get '
married in a RC church. So it is understandable that you would obviously have to have a civil ceremony at some point too.

I would like to suggest one more thing, I think that if you and your DF try hard enough you will be able to get his mother to reconsider her stance (as I am sure she is desperate to do so) by making her believe how neither of you had thought it through, and that when you both did, your DF realised he would be devastated not to have his DMum there when he gets legally married, and that you also wanted her to be there when you realised that the legal ceremony would mean much more to her than to your own mother, because of the reasons I mentioned above. Good Luck OP. I hope that both of your Wedding Days are lovely 🩷

I read about the abuse after posting my comment. You should have put that in the initial post, then would have got very different replies.

It sounds like this is entirely your fiance's decision and doing. If you aren't in contact with them why is flack from his family coming your way. Ultimately he needs to deal with his family, so any comments you get tell them they need to talk to him and make sure he isn't blaming you for his decisions.

This was a joint decision ultimately. It's on both of them unless the OP was saying 'are you absolutely sure, you know she's going to be super upset'. She admits she didn't. But again yes much more on the DP.

The MIL was always likely to throw a complete hissy fit and so what I don't buy is that if she was truly abusive that they didn't discuss how upset she was going to be. There was an obvious solution of the two mothers and the aunt. Either this is something that genuinely means nothing to OP and her DH, or it is really important and he didn't want his mother to be there for this moment.

I think the DP just didn't care about his mother's feelings, and the OP didn't actually care either (why would she) and just went with what he said without challenging why not his mother, and now they've suddenly realised that others actually do care so (the OP at least) is backtracking to not seem like a bad person.

It might be a good thing if this is a dysfunctional abusive family, but choosing your wedding day for this fall out is dysfunctional too, and that's the part of all of this that is most concerning. As I said, I would not have let DH do this on our wedding day - the options would have been to bring this to a head in advance and tell the MIL that they were going no/low contact, or suck it up on the wedding day itself and do that afterwards. Maybe the DP has such a history of abuse and disfunctional relationships he didn't see what he was doing (but then I sure as hell wouldn't be marrying him until he'd addressed that) but the OP should have seen what was coming as well.

The blame for the mother being upset is on the DP. It was his call. The blame for the massive mess and drama they now gave surrounding their wedding is on both of them.

I voted yanbu because we are doing the same thing. We've made it abundantly clear to everyone that we are not having a "Wedding", we're just going to sign the paperwork, maybe get lunch and then go home. Obviously having only two witnesses means we can't have everyone there but luckily they don't seem to mind in our case (including mil). It's entirely on your dp to deal with this situation I think

Just be the bigger person and invite them. But it should actually be your fiance who wants them there.

Is she refusing to come because you insulted her so badly by not inviting her in the first place?
You appear to have cocked up mightily here. His poor mother.

I don't think the couple is doing anything wrong, and this is not OP's issue to fix. It's her partner's choice and sounds as though it's for very good reasons.

But I will say that this is why eloping and telling others AFTER the fact is a better choice. It's always gauche if not rude to tell people about events they are NOT invited to. Just keep it to yourselves, do the deed and then joyfully announce your wedding after it's taken place.

OP I’m obviously in the minority here but I don’t see any of this as your problem/fault. You have offered alternatives and your DH has decided on a smaller room with less guests.

For everyone giving you a hard time I wonder if you have thought what kind of mother she is not to be invited to her DS’s wedding?? Being a mother doesn’t automatically give you an invite and it sounds as though it’s been his decision.

I’m not clear on how you’re receiving the news that the MIL is blaming your etc but from what you’ve said so far, she doesn’t sound like a hugely significant person in your / your DP’s lives for reason you’ve stated (which I totally get, by the way). If you care about what people are saying, I would get the message out there somehow that this is firmly between her and DP. It’s a shame she can’t take a good hard look at herself, accept the reasons why she’s not been included alongside the aunt and celebrate with you at the reception but I’m sure this ain’t the first time she will have made a family occasion all about her.

It's your day, one you want to look back on fondly for many years. We got married quietly at the local registry office, 2 best men and a maid of honour. We didn't want any of our toxic family there to spoil our day, they didn't find out till much later.
We had booked a beautiful hotel suite, champagne, earl grey and cucumber sandwiches. We didn't have a reception or party. At 5pm we left to take our dog for a walk around the park in wellies and our wedding outfits.
We look back on that day with such happiness it was perfect for us ❤️ that wouldn't have been the case had any of our family attended.
Family problems are a big reason many people elope.

Absolutely. I felt desperately sorry for his mother til I read the bit about the abuse.

You should’ve posted the context of his mum not protecting him from the abuse in your OP and you wouldn’t have gotten so many angry replies.
no you aren’t being unreasonable if his aunt is more of a mother figure.
however are you getting married in a cupboard?! Three people?

Imagine your own mother not protecting you from your stepfather's abuse.

I understand why he would pick his aunt over his mother, but it is still a choice that is going to have lifelong repercussions. Not including your parent in your wedding ceremony makes a huge statement.

I agree it sounds dysfunctional @marryescargatoire but I cant agree it is OPs responsibility. It is her DPs responsibility to manage his side of the family. There is no suggestion OP insisted on having 2 invites to his 1.

As for this It's also obviously not a situation where the mother has been so horrifically abusive long term that they are happy to not even care about her feelings or that the DP actively doesn't want her there - once the MIL got upset they were rolling to try to rearrange things so she could get there.

I disagree again. I worked with abusive families for over a decade - its very hard to break from families and most people try to have a relationship until they reach the realization that it is just too harmful - this can take years, or never happen at all, to the detriment of the victim. Or people live in fear of negative reactions from their family of origin. And some forms of abuse are more difficult to identify in a way - because people often dont feel like they should have the strength of reaction they do because 'it wasnt as bad as some people have', or 'it was nothing sexual' or 'I never got hit'. There is considerable evidence that low level emotional neglect or abuse is extremely damaging to the child.

For a lot of people. standing up to, or breaking away from an abusive family only feels possible when they have or start their own family. But then it is very easy for the abusive family to project the blame for it onto the partner.

To me, it sounds like the OPs DP is reacting from a place of trauma, rather than because it was 'not too bad'. But whatever it was, women are not responsible for managing all the emotions of entire extended families.

Imagine your child doing this to you, it’d be heartbreaking! Surely two more people isn’t going to ruin your wedding.

It's not and I've been clear that it's not ok that she takes the blame for his decision.

But OP is the one who came on here acting all innocent, asking whether they're in the wrong and acting like the MIL is unreasonable to be upset. Any body would be upset. I don't know if OP's father is in the picture but unless they are extremely distant he will be upset too (and he can see that she did her best with a hard call as she was going to upset someone). The blame is not all on the DP here - this was always going to be the reaction and OP admits she didn't actually care enough about the MIL to spare her a second thought. Fine if the DH decided he didn't care about his mother's feelings, and the OP decided to support her husband, but that's actually not what is being said (and it's certainly not how the thread started).

But yes of course the vast majority of this is on DP. I would have refused to entertain this as I've said because it is disfunctional to blow up your wedding day like this. If my DH actively wanted his aunt in this scenario, we would have gone with the two mothers and the aunt, and if he actively not wanted his mother there she wouldn't have been invited to the wedding at all, and we would already be no contact.

Am I the only person who read the OP properly? The MIL wasn't welcoming to the OP. Why should she be invited? It doesn't sound as if the OP's fiance is close with his mother, either.

You either have a wedding with witnesses you don’t know or you invite the equivalent people on both sides of the family. Therefore, if you’re having your mum & sister, he gets his parents & siblings (and any plus one’s I’d say). I had twice as many relatives at our wedding as DH did but that was because I have two siblings when only has one and one of my siblings is married.

Honestly, if you’re having six people at the meal, they should all be at the ceremony. It’s pretty hurtful, especially to his mum, to say that she’s not welcome.

Stupid question then.

Of course YABU.