AIBU for not wanting my sister to spend time with my ex

OP, your relationship with her is over.
She is toxic.
She 100% wants to hurt you.
Please consider reporting him to the police.

Her threat regarding Christmas is more drama.
This is very deliberate behaviour.
Stand your ground with your parents and her.

I’m presuming he is a coercive control type as well as the other stuff he did? Because forcing estrangements from family is a big theme in victimising someone. Presumably he spent your relationship working out everyone’s weak points ready to use, should it be required to keep you in line. It’s the same technique used to reach children: keep the ‘protective’ adults in thrall or under the thumb.

Don’t let your parents share anything else with your sister. This is probably all deliberate so you’ll a) reveal your hand, b) suffer emotionally, and c) fail in court. There’ll also be an element of punishing her for helping you escape him, and of needing a replacement set of victims to emotionally hoodwink, bully and manipulate.

Absolutely this.
Grey rock with sister.
her behaviour is completely unacceptable but since you say she is the golden child / narc, I’m unsurprised that something that so terrible that happened to you has still to be seen as impacting her and she needs to be the centre of attention.
When these things happen, they are showing their true colours, even if you knew it before, this kind of behaviour should truly cement it.
I have also had a similar experience. Consequently it has impacted my relationship on those family members. It’s taken years and years for them to listen to me and seem to come round to his behaviour but at the time, when I needed them most of all, they put him first.
Sadly, some people, like your sister is enjoying this.
Consider charging him.
Wishing you all the best.

Your sister is unforgivable. I would strongly suggest supporting charges because if not it also (wrongly of course) suggests the abuse may have not been so bad and this sense could impact child arrangements

Wow, your sister has basically chosen your ex over you. What a disgusting person she is. I too would be extremely upset and would find it hard to forgive.

Jfc.

I'm so so sorry. What a headwreck for you...

Wtf is wrong with her?
When was the last time she invited you over for dinner?
Did yout parents share the log?
What did she say?
Where are your parents in all this?
Does bil umderstand the batshit rationale?

So many questions

💐💐💐 for you

She hasn’t just stuck the knife in, she’s twisted it too. I hope you are getting more support from your parents. If she had been seeing him with the baby for another reason such as watching them to safeguard baby that would be different. It very much seems she has decided to support him.

Don't give into her threats at all

Many abusers present themselves well to other people. They are charming and kind and funny.

That presents a dichotomy to other people - you are saying he was X (hurtful, violent, disrespectful, abusive) but they perceive him as Y (kind, supportive, intelligent, amusing).

Then the abuser adds to the deceipt by painting the abused in a bad light - she was mentally unstable, deluded, she lied, she was cold toward me, maybe she had other lovers...

Your sister has been taken in by him as much as you were when you were together. He is a master manipulator.

I've been there, and it hurts. It took me 20 years to confront my dsis. And she was actually shocked. But at the time she couldn't have stepped back and seen how harsh her behaviour was.

Make sure she doesn't blab any of what you shared to him.

My sister would be dead to me, also, her thumbs up shows absolute contempt for you.

Well it's certainly incredibly tone deaf of your sister. It reminds me of the time my mum went to DC1's birthday meal with my abusive ex and DC2. I was very upset and I can fully appreciate that you are upset too. In the end though your sister is a free agent.

OP, the accusation alone and reporting him to the police will put the spotlight on the scum he is.

I am so sorry that your sister is similar scum to him.
Completely unforgivable.
Do not tell her anything about your life and plans.
Complete information diet.

She is dangerous to you.
She certainly doesn't wish you well.

I'm so sorry.

You are right to feel as you do. Cut her out. When you needed support she gave it then took the other side. What the fuck was she thinking? She’s stabbed you in the back. If my friend or family sided with my abuser they would be dead to me. So sorry she behaved so badly. You don’t deserve that after all you’ve been through xxxx

Your sister is a cunt.

Your ex had your daughter and youre worrying about her kids... Im on your side that's awful but why is he getting access. I hope you've reported him to the police and pressing charges

She’s disgusting.

Sorry they’ve done this. I’d see it as a complete betrayal.

Your sister is nasty scum.
Protect yourself from her.
Have you reported your ex to the police?
Talk to Women's aid and get advice and support.

I’m sorry. Perhaps because of my own experiences but I feel a sister should be there to support their sibling. I wouldn’t forgive this either.

How do you normally get on? I’m assuming your ex normally spent a lot of time with your sister, BIL and their children but I still think that could have been minimised or stopped.