I went to a counselor [the samaritans] about it and he couldn't believe how messy the situation was, he did not know what to suggest.
"The Samaritans aren't counsellors and they shouldn't /don't suggest what to do. (I'm an ex-Samaritan). They provide support by listening and not judging. They're not going to tell you what to do - if this is what you're looking for, try seeing a therapist instead."
I was going to say the same thing, the Samaritans aren't counsellors, and a counsellor or therapist shouldn't really tell you what to do either. They should listen to you and work with you so that you can come to your own conclusions about what you want to do.
We are in a similar position, a relative recently got engaged but I suspect we're not going to be invited to the wedding.
We are estranged from members of DH's family for good reason, but it's had a knock on effect through the rest of the family so one by one we've become more isolated and cut off. This relative was really the last one left that we had contact with but we can't see how we can go to the wedding.
If we are invited and we go, we will be there with at least three people we haven't had any sort of voluntry contact with in years.
There is no question of those people not being invited in favour of us, and we would never dream of giving an "it's them or us" ultimatum.
We know that they won't respect our boundaries if we go, so they will approach us, and that will be stressful and upsetting.
Which will leave us the choice of being trapped for the sake of politeness at someone else's wedding, or telling them to leave us alone and potentially causing a scene at someone else's wedding.
We can't go, even if we're asked.
I would only suggest that you speak to your brother in advance and have an honest conversation with him.
How he takes that is up to him but I think you need to do it as soon as you can.
Just a word of caution though, he may not take it well or understand why you can't just make up with her for his sake.
If you can offer anything else, like inviting him and his fiance to visit you shortly before or after the wedding, and have a celebration that way, maybe that will show you support him and will give you chance to discuss how you feel. And explain that although you would love to be there, you don't want to be part of any upset on his big day.