3) You are behaving badly, not talking to your friend because she is dating your ex. She is playing by the rules and you are being a sore loser.
2) You lied when you told your friend you no longer had feelings for your ex.
And because they are familiar with all the dirt on him, they wouldn't touch him.
However, if you and your ex didn't work out just because you just weren't right for each other and there was no real drama involved, what's the harm if your current girlfriend and someone you once loved end up together?
That would mean I might run into one of them occasionally and see him look at my friend the same way he once looked at me.