How Do I Know If He's Really Into Me?

Well from what it sounds like he just kinda wants to make his ex jealous or something to that affect. For some reason it makes you feel good, sticking it to your ex I mean. Honestly I wouldn't worry about it, and if it bothers you that much just ask him about it and if he hasn't done anything to cause you to mistrust him then take his word as honest. Good luck!

As you just said, they were over a year before prom, if he took you to prom and is still talking to you and stuff than he is into you. And what if his ex is trying to hurt you, she is probably jealous because she knows that her ex has feelings for you. And the thing about prom, it was the ex that said it if its not coming from him or a good friend and its bad it probably isn't true. So Don't worry. Hope everything works out and I helped you

Don't Chase him! Limit your calling and tracking him down. I have done this time and time again and it really works. If he calls or tries to find you then he is interested if he doesn't then he's just not that into you. Plus you could always check the book out. He's just not that into you.

Action speaks louder than words!!Good luck.