How do I get over this with my sister?

[BrennieGirl]

My DSis and I have always been quite close. I was there the night she met her DH, when we both lived abroad we used to visit each other a lot, both families go on hols together etc. We don't live close by but we see each other when we can.
I knew her marriage wasn't in great shape and a couple of years ago I found out that she had had an affair. She said it was over and she regretted it, still loved her DH etc. At the time I was quite upset at the thought of her family breaking up and things were a bit awkward between us.
I had my suspicions that the affair wasn't over and then 10 months ago she told me it was still going on and that she was leaving her husband. I was very upset again and she really withdrew from me (and the rest of our family). I realise there is no good way to split up, but she went about it in a really, really selfish manner (my other sis lives near her and they are also close so I got a blow by blow account). I've seen her a few times since at family events and we've been perfectly civil.
She has invited me to an event next week (I can't go) so I think maybe things are thawing a little. I'm not sure I'm ready (I keep coming back to her deceit and lies) but for the sake of our relationship I can push myself to go. However, there is one big obstacle; I don't want anything to do with her new partner. All I know about the man is that he helped split up a married woman's family. I have no respect for him. It also feels very disloyal to her DH. I really don't want to meet him and it would be massively awkward as he knows how I feel.
Reading back what I've written above, I sound like a sanctimonious old cow but I just don't feel the same about her any more. I want my old sis back. What can I do? I just can't see how things will ever be the same again.

You need to accept as a minimum having some sort of relationship with the OM to build bridges with your sister. You won't get your old sister back but you won't move forward putting conditions on it

This isn't about you. If you can't see past what she has done, do her a favour and keep your judgement away.

Remember, you were not a fly on the wall.

I have been in a similar situation to this although my sister broke up from
The person she had an affair to.

She did however move on quickly and I struggled with this however I have had to hide some
Of my feeling as one I didn't want to loose my sister and two frankly if a marriage isn't working that is on both parts and something mustn't have been working but mostly I put my
Feeling aside for my
Nice and nephews as the thought of
Not being in their lives is just unbearable.

Personally, my sister has done some god awful things and made some terrible decisions. But ultimately her happiness is what concerns me most. I get your upset with your sister, but that's her burden to take. We are a close family and we are very loyal to each other. Her partner might be lovely, she might have been totally miserable in her relationship and you don't know the half of it. Not excusing anything but I'd cut her some Slack. That's just my opinion though, I hope you get in a more comfortable space soon.

I think ultimately you need to know that your sister broke up her marriage. The OM didn't force her.

That's not to say you have to like what she did. You don't really need to be anything other than civil to her new partner. Just surface pleasantries should be fine. No need for deep conversation with him.

Affairs are so destructive and divisive for friends and family.

You won't get the old sister back, as she's likely changed over the years.