How to get over being mistreated?

In My last post I told a little about how I was taken advantage of by my neighbor and he is also my crush. Well. I can't stop thinking about what happened between us a couple days ago and i haven't eaten nor had an appetite. Anything reminds me of him and then I feel sick again. The kiss and everything. I thought he liked me but he has a girlfriend. I feel like I keep falling on my butt at the skating rink and that I can't get up. How can I stop thinking about him?