What a loser....
The worst thing is he sends the pictures to your friends. Obviously they will be a bit grossed out but ultimately I would not think badly of you if I were your friend. I would ask him why the **** he was sending me a naked picture of his ex-girlfriend? And basically consider him a total freak to be honest.
I don't think you have to worry. If your friends are horrid to you about it they weren't worth it anyway. I somehow think he will come out of this a lot worse than you.