Ok short version.

Really like this girl. Think girl likes me too. Girl has been seeing someone for a few months. I most definitely will not do anything about my liking this girl because of the fact she's seeing someone. Need to get her out of my head but I just can't stop thinking about her... Help. How do I get this girl out of my mind??

Stop sitting around thinking about it. Fill your mind with other things. Go for a run. Play tennis. Go swimming. Go out with friends. Do something you have been wanting to do for a long time. Meet other women.

You know, I could go on forever - but you get the point.

Do you have evidence to prove she likes you?

Ah man I'm over it now haha