I have only had the experience of exes getting married a could of times. I know there will be a time before I know it when more will be getting married but I will jump off that bridge when I come to it.
The first one was my first "real" boyfriend, if you know what I mean. I was no longer thinking of him THAT way and really didn't want much to do with him, although of course I wished him well. He stayed in touch with my mom however and invited her to his wedding. The picture he sent of his wife to be looked frighteningly like me. My mom did not go, and I mentally moved on. He will be forever more known as J, they guy I broke up with in the parking lot at Home Depot. Not to be confused with J, annoying work guy.
The second time this happened wasn't really an exboyfriend, just someone who I went out with a few times (like to prom. twice) and we got kissyface, but nothing further because I was not ready for that. HIS wife to be, although we were friends in school, didn't care for me once they got together. when the invite arrived, it was addressed to D and Guest, although D and I had been together for nearly 5 years at that point and were living together. I went of course, the groom was and is a dear friend. And I would go again, it was a fun wedding. They're divorced now, and the rest is another story.
What would I do if I were caught in that spot again? I'm not sure. If man #2 were to marry the woman he is with now, I wouldn't think twice about going. she and I are friends and I don't think she sufferes from the same insecurities as his first wife. if T were getting married, I would probably spend the whole day in bed. If D gets married, I plan to be there if invited. but we are all friends and any insecurities would be mine. who knows, by the time T gets married, I may be done crying. but based on today, I don't think that will be soon.
Hell is when the man you can't seem to let go insists on finding you a new man. I'm proud of myself for telling him it upsets me. Maybe now he will stop.