Most Helpful Guy
Part of it depends on if you are single or not. If you are no longer single, you need to ask your SO for permission. Normally I would say befriend who ever you want they shouldn't be able to demand you not, but would you want your SO to get friendly with their ex. If you can show him that both of you are not interested in each other and he approves great, but that is something I would respect. Same thing if he is taken except it would be with her permission.
If either one of you is taken and you have permission, do what ever you want to do as friends, but if you find you or him lying to hide what you do, step back or cancel the friendship. That is the sign of cheating or at least getting close to cheating.
If you are single, that is between you and him and how you left your relationship. Its still a little weird, but it could be 2 seconds or never.
Most Helpful Girl
I hand out with my ex husband no problem, even when I had a boyfriend. No sex I mean. Now that he is ex and I don't have to put up with his BS I like him.
So it ok to have time alone with ex when it feels right