Husband and I are very close friends with another couple. The men know each other from school, we met through them and subsequently became very close friends. He was our best man, she was our maid of honour, that sort of thing.
Last summer, they told us that they were separating for a while as he was having doubts about their marriage. They said they were going to attend counselling and try to make it work again in the new year.
A few weeks ago, we went out for my husband's birthday, and the husband, Rick, came down for it (they live 300 miles away, he still lives with Sally) to our home town. When we arrived in the pub, Rick announced that he'd brought a date, Tara, whom he's been seeing when he comes back to our home town. He informs DH and I that Sally doesn't know about her yet.
Well, fucking hell, Sally is 300 miles away assuming you will be getting back together at some point!
I was upset on the night out, as I felt I'd been blindsided a bit by this, and I hated the thought of hanging out, playing nice to the OW whilst my good friend has absolutely no idea this is happening. Husband just shrugged it off, his decision to make and all that.
Tomorrow, my BIL is having an early evening birthday party, and then we are all going into town to celebrate Paddy's day. Rick is coming down for this. He and DH will also be watching the rugby at our place in the afternoon tomorrow. He has messaged this evening to ask if he can bring Tara, the OW, with him to our place to watch the rugby. DH is fine with this, and I won't say she can't come over, as it's his house too, his old friend, and it should be perfectly fine to have his friend's girlfriend over.
However, I intend to be out at the time, as I still can't stand the thought of sitting, the four of us, in my living room, playing couples hanging out like everything is completely fine. I feel like that wouldn't be good behaviour towards my friend. I'm also considering bailing on the evening out.
AIBU to react like this, and avoid spending time with the OW?