To not forgive?

It sounds more like she's gaslighting you than doing anything to deserve your forgiveness.

I couldn’t forgive her. She has ruined your wedding and made the whole thing about her.
I hate it when people who behave in cruel/spiteful/unhinged ways turn it around on the person they’ve hurt - the victim becomes labelled ‘unforgiving’, ‘bitter’, ‘cold-hearted’, ‘not family orientated, ‘awkward’, ‘controlling’ etc. And it’s utter bollocks. It’s done to transfer the blame and is extremely manipulative. It’s not really forgiveness when you are being forced to do it either. Forgiveness for me is accepting what the person has done, understanding it was a mistake and being able to move on from it. But in your MILs case it wasn’t just a mistake. She tried to control your wedding for a prolonged amount of time and then got people to turn against you by making them choose between her and you when she didn’t get her own way. If you let this go and then go onto have children, she will be doing this with your children in the future. She will likely do it with any event you have in the future too. She can’t be trusted.

The problem here (for me) would be that forgiveness really requires the behaviour to have stopped. Your MIL is still trying to control you, she obviously doesn't regret what she did, and she sees it as your place to get over it and give her the family life she wants.

I have a pretty awful family. Worse than your MIL sometimes. I have forgiven them all. How? Distance. It's easier to forgive my violent father and sister, my spiteful and manipulative mother etc, if I don't have to have any contact with them. My presence is what sets the behaviour off, so everybody benefits if I don't ever see them (to be clear, I don't do anything, it's literally my existence that "causes" it).

What really helped me was working out the cycle of behaviour- the gifts and attention to draw me in, followed by unreasonable demands, which lead to physical and/or emotional abuse when I refused. Then there would be a long period of ignoring me, until the cycle started again. If you can break the cycle by changing your own reactions, then you are home and dry. It sounds like you are well on the way to that.

Like hell would I forgive and forget this. I’d never see or speak to her again.

YEESH!!!!
I wonder if 'dear' old FiL had any say in his wedding, or if his future wife and MiL just told him how things were going to be??
Does he have any say in his life? Or does she wear the trousers?
I'd have gone on with the wedding, if they turned up then ok, but if they didn't then at least you'd have known there'd have been no interruptions!!
I do feel for your DH, but at least he does seem to have a spine and a mind of his own, at least some of the time!
When/if you have children, PLEASE set up some ground rules from the start that HAVE to be adhered to by ALL!!!
Were your parents not around to help with the wedding? If they were, I'm surprised there wasn't all out war between both sets of parents - I'd have been telling the old bat to butt out, she'd had her day!! 🤣
She's obviously used to getting her own way and not used to another woman in the family, or even not in the family, having some sort of say in things, especially in their own lives!
STAND YOUR GROUND, or she will always be thinking, and no doubt letting everyone else know, that she is above you and you kowtow to her!
She sounds like a proper nasty bitch!!

Absolutely bloody well not. I would not forgive her batshit antics prior to your wedding in a million years.

This sounds very sensible OP!
You could say yes you forgive her. Mainly because she is presumably unhinged ( don't say that part).
But due to her actions there is so much disappointment and hurt it's not clear if she can ever make that right so things will always be different.

Yeah it’s a big fuck no from me too.

It seems that they are trying to minimise what happened and just gloss over the event and the subsequent impact. I’m all up for a quiet life but not at the expense of my sanity and this unacknowledged chasm between what’s being said now and what was done then would drive me CRAZY.

You might not ever get closure but you don’t need to participate in the delusion

Well what do you want the outcome to be?

Her behaviour sounds unhinged and you'd be reasonable to go NC or LC because of it - in which case that's your answer. You don't want to be around her so you don't need to forgive her. Up to you whether you feel you can handle this grudge hanging over you.

If you want to maintain any semblance of a relationship and if her apologies are genuine, though, you'll need to be magnanimous.

There is a difference between forgiving and forgetting.
I've told this story before, from my confirmation class. The lovely priest taking the class, when a little boy, had a silly squabble with his sister, and in a fit of childish rage, stabbed her arm with some scissors. He actually loved his sister dearly, and was instantly remorseful. She accepted this, and forgave him. However, she bore the scar on her arm for the rest of her life.
Some actions have consequences that cannot be undone.
You can be the bigger person, and forgive her, so that the resentment doesn't eat you up, but the damage she did cannot be undone. In fact, it appears that she is not genuinely remorseful, but is avoiding her own sense of guilt by trying to minimise her own spiteful actions in her own mind. Even if this breach can be healed, things will never be the same. She had the opportunity to treat you as the daughter she never had, and comprehensively blew it. If she can be so spiteful to her own son, and then try to laugh it all off, she can really only expect restrained courtesy from you, moving forward.

It's not that hard. Why can't OP never speak to her again? Even if she does have children. She doesn't have to say a word with her and certainly doesn't have to treat her with any civility

She simply doesn't come into her home or come around her. And should there be children then DH can take them off his own back when they are old enough.

If I were you any children I had would only have very limited interaction with them and only then if DH really insisted they had some contact but you don't need toxic fuckers like this messing with your kids head. They wouldn't be allowed in my house tbh.

I hadn't seen the update....that does seem very extreme.
First your DH needs to make it clear the fall out is not over not having the wedding you wanted....the fall out is about their behaviour.
And that behaviour was so extremely upsetting its difficult to forgive.
But you don't have to forgive or forget to give a second chance, or be cordial.
You don't have to hold a grudge or continue to be hostile.

You can and should be cautious, but for your OH sake try and rise above and just accept she's who she is.

Seriously I would go fully Non Contact and not allow her newr any children you may have. She has already seriously fucked up her son do not let her fuck up any kids you have

Your DH needs to come down hard and stop allowing this.
You block her on everything and tell DH he has decided to allow that toxic bitch back into your lives but that doesn't mean you will continue to suffer.

So you don't want to hear anything of her or about her again. He doesn't tell you a single thing. Not what she said, what she's doing, what she's thinking. You tell him you will never speak to her or forgive her.

He can have whatever relationship he wants with her but you have chosen your stance.

Oh no no no, I could not forgive or forget that one, these people would be dead to me. I've cut both my SILs and have no intention of having a relationship ever and they aren't this bad. You crack on and ignore them hon 💐

I understand after the update that you may never fully forgive her and you'd be justified.
But what does she want to see as a result of the 'forgiveness'? what are you doing / not doing that she wants? Are you not speaking at all to her? If so, that'll be hard to keep up forever, especially if you have children. You don't need to forgive her to agree to speak to her / be civil. If you can manage that then 'family life' whatever that means can move forward.
She can ask you to speak to her, treat her civilly, even show friendship, but she can't ask you to fully forgive down in your heart nor completely forget and actually I think you shouldn't forget - you should remember, and be on guard with her.

I couldn't forgive that unless MIL showed genuine remorse, took responsibility for her actions and apologised profusely.

Oh wow. Your MIL is a massive cunt.

You are completely right to never set eyes on her.

Dear god OP, she sounds absolutely unhinged. I remember some of your previous posts about her and the wedding. How incredibly cruel they both were to DH, and over a long period. Absolutely not something that can be brushed under the carpet with a bunch of flowers if you ask me. No way

It doesn't defeat the object of wanting forgiveness
The message you need to give her/your DH needs to tell her that she needs to apolog6and show remorse.
Then you move on

Could you send your PIL a message outlining how much your MIL upset you and your dh over the wedding planning, and how hurt you both were at the threats and ultimatum that they issued as a result, @Rattymcratty - and emphasise that this what made you cancel the wedding. Explain that you saw how unhappy that they made your dh, and that you too were upset by her interfering and the ultimatum, and that both of you need them to acknowledge how wrong they were, and apologise properly for it all.

Ideally they would not need to be told how they overstepped the mark, and how much pain they caused, but it seems as if this is very unlikely in this case.

After your update a big fat NO from me.

Your poor Husband and poor you.

The thing is, what if you don't forgive and move on ?
what happens if you have children?

Will your husband be able to emotionally support you, or cave in to the emotional blackmail.

I don't envy your position OP and both in-laws sounds bloody awful.

I’ve been in a similar predicament (different problem FiL went over a physical boundary with me, husbands family went sustained nuclear attack at me and husband for it - very dysfunctional emotionally family). I’ve been asked the same to forgive and forget, move on etc.
I ’ve asked myself similar questions and come to realise forgiveness is for the ‘sinner’. In order to live with what they did. Husbands family will never understand what they’re apologising for. So it can’t be genuine. I don’t trust they’ve learnt to never do what they did to anyone else again. So I won’t verbalise it or offer it.
But I can be in the same room as them (except FiL, working towards that still after his assault), and be civil. It doesn’t eat me up inside, but there is a level of acceptance that I lost genuine family members and it’s difficult to trust or see them the same way now however much I want to.

😮
No. I don't think I could forgive that.