I agree with Jessica. Although there is nothing sexual going on with the ex, sometimes an emotional tie is worse. You are playing with the emotions of two people here, and it's not really fair. I've been in a similar situation and sometimes you just need to go with your instinct. Do you think that things will change with your current boyfrined? the fact that you were dating someone he knew while you were broken up with him might be part of the reason that he has closed himself off from you, maybe he feels a bit betrayed. have you talked to him about it? The other guys, do you think this is just a temporary thing or that he will stay being the way he is right now? you never know how things are going to end up. but i would make a decision, you never know... time could heal all wounds and you may stay friends with the other guys...
you could also just forget about both of them and start new... i make it a habit to not go back to the old... as much as some people change, it's very rare... sometimes people just make better friends.