Is it normal that i still write my ex?

Here's the story, as short as possible... He lived in one city, I in another. Same state. We met when i was visiting a friend there... Basically I got drunk, he liked me (we did nothing, he just sat next to me instead of her...) and she got mad and left me at his house drunk with no phone and not knowing who he was. Oh also, she had a boyfriend. Okay well, after that we obviously got to know one another and I started coming to visit him once a week, and we started dating.

A few months later, I moved and we were living together because he'd gotten into some trouble with the law... (bad for me to stay with him, yeah I know that.) well anyway, the way it worked was he lied to me about drug use and didn't tell me he was already on probation. When it all came out, I was accepting about it. I loved him and everything in out relationship was fine so I didn't really see the issue.

When he got off ALL of his probation and got back on track...he dumped me. Right out of the blue. Just didn't come home for a couple days (first time ever doing that) and he told me he didn't see a future with me anymore. Then he told me it was because I'm crazy. ???? WE NEVER FOUGHT.

Well the problem is, now I am crazy, because I can't get over him... We broke up over a year ago and I still occasionally send him messages updating him in my life, letting him know I'm thinking about him and that I hope everything is going well for him... And why do I do this? I have no idea... I can't help myself, every time I send him a message I really hope he will reply, and he never does. I just keep hurting myself and I can't move on.

Is this normal after a first love?
Why do I keep doing this when I know he doesn't want anything to do with me...?