What should I do in this situation? Guy I like's ex came back... eh?

Sorry this is so long, but please give me your advice?

A few months ago I started 'talking' to this guy, and we recently finally started hanging out. Sometimes I got the feeling he likes me, and other times it's like we're just friends, and he never made a move or anything. Well, I finally asked him if he likes me or not, and he says yes, but he's indecisive and doesn't want to hurt me. The next night we hung out, and he told me about how he has this ex-girlfriend who just moved back into town, and he's not sure what's going to happen with her. SO, that's why he never tried anything, because if we start getting closer than it's going to hurt me even more if he's not available, and he doesn't want to "put me on hold" because obviously they're just going to break up again like the first time. The very next day, he called me and said that we couldn't hang out anymore, and it's an "ex thing" so there's not really anything I can do.

Now, he even told me they're a terrible couple but whatever, so I'm not sure how long it's going to last this time around. I've been single for about 2 years and this is the first time I've liked somebody again, so it hurts even more. Does it seem like I have reason to be mad at him? When he was telling me about all this, I just kind of said ok, that's fine... But now I feel like complete crap. What should I do if, a month or two down the road, he wants to date me? I don't want him to think I'm that pathetic...

Thank you so so much for any advice, and don't be a jerk :-/ I'm so bad at relationships, lol :-P