Okay minor relationship dilemma:

I was in a relationship for over five years. I still have very strong feelings for my ex (which he knows about). I've been trying to slowly pull away from my group of friends (I mentioned this in another thread here) because I think it will make it easier for me to get over things. But sometimes it's hard to pull away since I do enjoy their company and sitting at home alone is kind of lame.

Anyway, earlier this week one of my friends sent out an invite for a show tonight. Went to about 10 people including me and my ex. (My ex and I have both both been present at a lot of events since he and I broke up since we have the same group of friends.)

My ex responds to the list by saying that he will be there and will be bringing the girl he is now seeing. That's the first time he's acknowledged to the group that he's with someone new (at least the first time as far as I'm aware) and also the first time he's been to a private event with someone new. I saw him at a large party once with her recently, but it's not the same. Obviously I'm uncomfortable at a small gathering with them present, and I had already bought my ticket (non-refundable). So I'm not going. But here's my question:

Should I tell my ex that I think it was insensitive on his part not to at least warn me that he was thinking of coming and bringing his new girlfriend? I mean obviously he doesn't have to clear things with me, but considering it's a very small group of my friends (and that he knows how I still feel), he might have asked me how I felt about it before announcing it. Is that unreasonable? Or will I sound like an immature whiner if I say something like that? It has been a while since we broke up, but of course that's hard for me. Especially given that most of our friends are in couples (it'd sure be weird for me to attend an event with a bunch of couples, one of whom is my ex and his new girlfriend).

I'm pretty sure I'm just going to disappear from my group anyway, but I wondered if it was a good idea to say something like that. What do you guys think? Ignore it and move on?

Sidony