To rip MIL a new one?

Have you considered emigrating?

A massive amount of physical distance - over 3,000 miles to Canada or 9,000 miles to Australia - might be the only sure way to enforce your contact wishes on both mothers.

I have thee adult children plus 2 DILs. I have a good relationship with all of them because I don't behave like a twat. I wouldn't dream of doing what OP's MIL is doing. If she is doing this because she is hurt by not being able to attend the wedding of her son, that means that she is doing this deliberately to upset and cause problems for OP which is unforgiveable.

Why don't you think I'm applying it to OPs MIL?
Just because one person is behaving irresponsibly and ignorantly doesn't mean we shouldnt try to be better. It's easy for strangers to suggest the OP drive an irrevocable wedge between the family - we don't have to live with the consequences.
Dialogue and understanding are the mature solution. It's clear that the mother and son have a relationship - yes she's acting unreasonably, but I'm guessing she's hurt by not being able to attend the wedding of her son.
I'm also guessing you don't have adult children.

You say that 'we should never behave in such a way as to cause others pain if at all possible' but you don't apply that to OP's future MIL. She knows she is causing OP pain and either just doesn't care or actually has some malevolent intent.

OP said:

'MIL has taken it upon herself to try and forge a relationship with my Mother despite having never met her and despite being told not to.'

OP's DH has tried to reason with her countless times and has told her that OP has a difficult relationship with her mum. Her MIL is passing on information about OP's life that is leading to further abuse from her mum. Even if OP's MIL is widowed, it doesn't give her a free pass. If DH and OP go low/no contact with his mother, it doesn't necessarily follow that he will resent it in future and go behind OP's back.

There is an easy solution to all this. OP's MIL and OP's mum aren't friends. There was no reason for her MIL to contact OP's mum in the first place. She should stop seeing her and stop telling her things about OP.

Everyone here is saying what she should do, or you should do. But all resolutions come ultimately from dialogue. First, ask why she is intent on ignoring your and her son's requests, in order to gain insight. The answer is unlikely to be "because I don't care what you think and I'm so selfish I just do what I want". It may be a misguided but well-meaning attempt to build unwanted bridges. Explain calmly that you are unable to meet her this year in order to protect yourself from the emotional impact of her contact with your mother.
One day, in perhaps 30 yrs, you may have an inkling as to how it feels to have grown up children, forging their new family and moving away. It isn't easy. Until then, try to be generous and not cause family division and force your DP to choose between you or his mother. He'll choose you, and in future resent it and begin to go behind your back. You don't say anything about his father, so perhaps she is widowed? She's had enough pain if that's the case. We should never behave in such a way as to cause others pain if at all possible.

It sounds like your MIL may have various motivations here;

1. she wants to know more about who you are and what your background is, and thinks that she may discover this from your mum.
2. As a mother she feels aghast that another mother in the equation is not included and she wants to know why/ is trying to be inclusive.
3. ‘It’s complicated’ isn’t sitting well with her and she wants to know what her son is getting into.

In any of these cases, she is way overstepping. She doesn’t know what the details of your background are.

you have some choices;

1. you tell her. You tell her that you were in a neglectful situation and officials had to be involved. She may approach you with more understanding and sympathy, but she could become more judgmental, depending on her personality.
2. you don’t show up. You let them forge some sort of relationship and your MIL finds out, herself. This may however take time, which may be uncomfortable.
3. you go low- contact with both mothers. This is an option others have suggested, but to me in doesn’t seem worth alienating a parent from your partner, in the long term, unless she genuinely means harm.

I'd be worried that your mother would be at your MILs house to "surprise" you.
I would be saying if you don't stop you will
Be banned from a relationship with any future grandchildren. If that doesn't get her to stop she never will. X

You poor thing, you must feel so vulnerable.
If you feel up to talking for the hundredth time to MIL, say you had hoped for a relationship with her that you missed with your neglectful mum, however because she has decided to have the relationship instead with your mother you need to back away..
You could write it as she can't change your words, keep it that short as you've told her numerous times the reasons why and she's chose to ignore you.
After this, back off unless she comes to you with empathy and an understanding of where you are coming from.
All the best OP, I can see she's triggering trauma that you have been trying to deal with.
Christmas is a hard time of year when so many are not joyous because of life situations x
So glad your partner is supporting

How boring.

You told me I needed to read properly when I had done so! I was showing you the post I was replying to in case it wasn’t clear amidst many posts on the thread. I think the ‘Quote History’ thing is relatively new…

OP has said that they are getting married abroad just the two of them and haven't given their families either a date or a time due to the behaviour from both mums.

You sound as though MIL being hurt and getting back at her future DIL by contacting OP's abusive mum and giving her loads of information about OP that her mum then uses to continue the abuse, is a perfectly reasonable thing to do. It really isn't.

I would think long and hard about actually going through with the wedding. There is no way my husband would be continuing to see his mother at all if she had behaved in this way towards me.

Be careful he doesn't say the right things but continue to see her by himself. Then, once you're safely married, apply pressure to start seeing her again together to make things easier for him. He may tell you that it's all in the past and she's changed. In your position, I would be holding off on any wedding for a while to see whether he continues to see her and under what circumstances.

Now did you decide this before or after she stuck her nose in because if it was before she is probably feeling terribly hurt and just getting back at you .I would hate to be excluded from my childs wedding

You can stop patronising people.

So glad you can read.

Let her have Xmas with your mum.
Don’t go, she is crossing very clear boundaries. And judging you for it.

The OP is in her late 20s, not a teenager.

Child protection orders are not put in place because the child has a strict bedtime.

Nobody is under obligation to bend themself into knots to avoid "causing pain" to a parent who treated them so badly as a child that a CPO was in place.

What a sanctimonious, victim blaming load of utter bollocks. OP was a victim of abuse and neglect by her mother and was nearly taken into care. There is absolutely no reason why OP's MIL needs to contact OP's mum. She is giving OP's mum information about OP which is enabling her to continue the abuse that started in childhood.

OP's DH has asked him mum to stop doing this but she won't. Therefore, the only way to stop her passing on information about OP is for OP to stop seeing her MIL and telling her anything.

The cruelty and brutality is coming from OP's mum, enabled by OP's MIL.

Her MIL isn't a nice person.
She thinks she knows better than the OP and her son.
She likes sticking her nose in.
It gives her a buzz.

People who accredit such behaviour as benign are wrong.

She is not a nice person and she will cause the OP grief.

She should rethink the marriage or insist that she has nothing further whatsoever to do with his mother, she never comes near their home, and he NEVER tells her anything about their life together.

Probably unrealistic, so rethinking the marriage is the way to go.

His mother will always think she knows best and will trample on their boundaries if she can.

You don’t sound very compassionate to me, OP. Sorry. I need to hear all sides of a story before I’ll buy into a narrative where one person describes another person as ‘a narcissist’. For all we know, it could be you who is the ‘narcissist’. I’m also very cautious about people who blithely talk about going no contact with family members. It is a cruel and brutal thing to do. You’re very young. By all means hone your assertiveness skills and protect your boundaries, but do try to do so without causing terrible pain to others.

I was replying to the OP’s post where she said it’s not uncommon for it to be used about a child. I can read, thanks. You can click on ‘Show quote history’ to see what posters are responding to.

Have had this exact same situation, sadly the ex chose the mother over her own family. I had several coffees with the M.I.L and also received a letter of apology (if "I'm sorry you feel that way" qualifies) over the years but nothing ever changed with constant sniping and inteference, it felt like being under a microscope everytime I breathed. It may feel great in the moment to rant but people like that don't care and don't change. You are better off having a rant with an unconnected friend and just not going and cutting all contact. Trust me, I've been there.

Go no contact with your MIL until she complies.

The phrase was used about an adult, the MIL. It was not used about a child. You need to read properly.

I have nothing against vulgarity in an adult context but do find it a bit grim that people would use that phrase about a child. I know lots of my relatives would use similar level language about children and I don’t like it at all (or calling children dickheads BIL).

Anyway OP you’ve had good advice, go low or no contact. Don’t let anyone hinder the progress you have made in therapy. Maybe time for your OH to get some help too.

The MIL thinks she's doing the right thing, she's naive. Maybe you could write to her explaining things again. Then she'll have time to absorb it properly.