Could You Be Friends With Your Ex?

Is it possible to stay friendly with your ex when he/she has really broken your heart with infidelity?  First of all, if you have children together, you must maintain some kind of "niceness" between you to make sure that your children don't suffer from the fall out.  Children are so precious, and so innocent and deserve to have both parents....so, aside from that, what about when your children become adults? I think that this all depends on how much time has passed since he/she crushed your heart and the time since the break up. I can tell you that even though I no longer dwell on his cheating on a daily basis, the pain and hurt is still there, but it's lessened because I no longer have to see him daily, nor do I have to deal with it any longer. My ex doesn't hardly EVER come around to see our daughter so I haven't seen him in a very long time.
I think that after all these years, that if saw him somewhere, we would be able to talk, but as far as being friendly enough to go places together, I don't think so....although, some people are able to put their differences aside and do so. I don't think that I would be able to go somewhere that he and his other woman was, even after all this time, however.....if I ended up at a party or a function where they were at, I would be able to make the best of it....after all, it's done.