when your pain subsides

I guess the problem is, I don't see an end to it. I'm better than I was, but I still cry and still hurt and still wish things were different. And it's been 9 months. I don't see myself ever trusting anyone again. That's something I have to deal with. The thought in the back of my mind that even if I do everything right, it might not be enough. The knowledge that a person can go from "I want to marry you; you're amazing" to "I'm involved with someone else," in only two weeks time... after you've been together for years. That sort of wound doesn't just go away. Even if the pain stops, it probably won't go away. Even if he came back, it would hurt like hell.

but spending ages moaning about it instead of just learning from the experience and trying to do better next time isn't going to help him, her, or anyone either of them is involved with in the future.

That's true, I suppose. Him being sorry won't magically erase his actions. It happened, and nothing can change it.

Part of getting over a hurt is accepting the idea that the person who hurt you isn't going to feel bad about it forever, and you don't need that kind of revenge/repercussion on them in order to feel better

I don't feel like it is revenge. I could have had a grand, Count of Monte Cristo revenge if I hated him or wanted to hurt him. I knew all his secrets. But that's not what I wanted. I just don't want him to treat it lightly, like it doesn't matter. Because it matters to me a whole lot, and it has damaged me a whole lot, if I am honest. I don't know if the damage will last a lifetime... but right now, I don't want to picture him happy without a care. Partly because I'm selfish - and I'm allowed to be, for once - and partly because it would feel like insult to injury... injustice.