SIL keeping BIL away from family

[AIB78]

So nc for this and apologies if its long and or confusing. My DH has three brothers, all fairly close in age and live locally. One of his brothers is with his wife a long time and they have teenage kids. A few years ago his wife had an affair but he stayed with her. Since then myself and my DH have not spoken to her as we were very hurt by what she did and my previous husband cheated on me so it brought back bad memories. She did have some relationship with other family members but nothing really now.

My problem is over the last couple of years BIL has pulled away from all of his family. They no longer attend any important family gatherings, birthdays, funerals etc but this was the first year BIL and their DC did not visit PIL on Christmas night. He visited it earlier in the day with them. SIL hasn't visited at Christmas since the affair.

I get on with my other BILs and SIL and we are angry that BIL is choosing to do this. Being honest we don't really want a relationship with SIL but it looks like in order to have BIL in our lives he comes as a package deal. How can we navigate this? Do we just suck it up and get on with her for BIL, although I don't think I could be that fake to somebody I actually despise.

This is a very short version. Its going on seven years now.

That poster is hilarious.
Slightly different situation, but my partner left his wife for me several years ago. Obviously it caused a lot of angst in his relations with his family for a little while, but they saw we were going to stay together and decided to be the grown ups and get to know me and we now all get on well.
They also keep,in touch with his ex wife and it's all very civilised.
Affairs happen and often it is not black and white why it happened. All family need ti do is butt out and be supportive and not judge. Or if they do, then don't be surprised if they lose contact with their family member.

@daliesque They weren’t deciding to ‘be the grown ups’ so much as damage limitation from some quite selfish actions. I wonder if he cheated on you you’d have the breezy ‘affairs happen’ outlook

@Wristfolds no they were really being grown ups who managed to keep their noses out of their son/brothers personal life.
If my partner cheated on me then my response to the affair would be dependent on whether he wanted a fling but wanted to stay with me (we'd work on it), or whether he'd fallen in love with another woman and wanted to be with her - in which case why make us all miserable by continuing to flog a dead horse?