However, you're obviously asking because you're unhappy with this...
Best thing you can do is not contact him or make any effort to get near him in whatever setting you may be likely to encounter him.
Ensure you look your best when you're out and about and start or keep training to get or stay fit...
You'll feel better and he may start wondering about you. Either he or his mates will see you and he'll know you're looking great and getting on fine without him. When this happens he's likely to contact you to find out what's going on in your life, who you're seeing and he'll try to get 'with' you.
At this point you can take control back (he has that at the moment). You play it cool and make yourself unavailable... hard to get!
Play him at his own game.
It's not easy but you'd be surprised how fast you can turn things 'round if you play the 'game' right.