I like this guy, but...?

Theres this guy in two of my classes that I like and who likes me and even said he'd date me, except for one thing- his ex is a psycho and it's preventing him from dating me. I want to date me and it's not fair that he's afraid to date me because of what she'd do. He's very popular and I'm more with my clique of kids that are mostly flippers, skas, and my friend Malina who's more "emo". He's over the ex but he's afraid of what she'll do if he were to pursue me even though I'm not afraid of her. I've also heard other people say she's the jealous ex type and that she'd start stuff but I really am interested in this guy so what should I do? thanks in advance!