I was going to lead off with an unfounded generalization. I was going to say, "It's weird going to your ex's wedding." But instead of presuming to speak for everyone in the world, I'll revise and just say it was weird going to my ex's wedding. I get along with him just fine, obviously (otherwise it would have been quite weird indeed to show up at his wedding...), and I adore his family. Walking into the church and being warmly, delightedly greeted by his sister and brother and catching up with exactly how much the nephews have grown made it feel like a family reunion. The reunion of a family I don't quite belong to any more, or at least belong to in a relationship I haven't figured out yet.
I got through the ceremony without a single one of the welling tears escaping my eyelids, mainly by pinching the fingertips of my left hand in succession just short of the point of drawing blood.
It was maddening because I didn't know where the waves of emotion were coming from. The girlfriend was next to me crying like a... well, like a copiously crying person the whole time, but she also cries at Hallmark commercials so I don't think our tears were springing from the same well. Maybe it was because the last time I saw him in such a tuxedo-clad setting slipping a ring on someone's finger, it was me on the receiving end. Which makes no sense since I have no desire to be married to him or to any man, for that matter.
I just wasn't prepared. I don't think there's anything in life that really prepared me for that. The divorces I grew up with involved the salient parties pretty much hating each other's guts, so the proper place and behavior of the amicable ex-wife at the next wedding was never properly modeled for me. I wanted to hang with the ex-in-laws at the reception, but didn't want to barge in someplace I don't quite belong any more.
The next few weeks and months will be a learning process.