I have a personal perspective as far as this friends business goes and it comes from past experience. I was m and d once before. I think the circumstances behind a sep/div will sometimes determine the nature of a friendship between an ex. However, nep was right when she says it takes a lot of time no matter what.
I think that element of infidelity makes a huge difference in what the aftermath of a D or separation will look like. At least from a Man's perspective. I've learned from you Ladies on this board that Woman seem to be better equipped emotionally to maintain a friendship with a cheating ex s. Not the rule by any means, but my own observation. I see that less likely with most of the Men on here. Woman seem to be more capable of separating friendship from a committed relationship. Speaking for just myself, I can't separate the two. I'm committed to my friend's well being and wouldn't do something like that to them. It's a matter of respect.
My first W and I didn't cheat on each other all the way up to signing the papers. There was some disagreement, but very little animosity or hard feelings. We parted with respect for one another as human beings if that makes any frikin sense..lol. Our youth may have made a difference, but I was married to her for as long as my current stbx. It was easier for us both to heal from this. I was the first to have a serious relationship two years later.
Don't get me wrong, I can forgive my current stbx, but friendship to me requires qualities she no longer possesses. If I were to meet her as a stranger today and knew what she had done in her marriage, I doubt I could be friends with her.
Maybe this is a character flaw on my part, maybe others feel the way I do. Just my penny's worth!
"It is curious that physical courage should be so common in the world and moral courage so rare." -Mark Twain