Having a very bad crush what probably won't work out, and I don't know what to do

TL;DR: In love with a great friend what very likely won't work, what to do?

Hey friends, I have to get this off my chest. I have been here before about 2 months ago, but my head kept spinning and my thoughts kept racing. I have a crush on (even more than 2 months ago) a very good friend (both male). He is very touchy, although it isn't as clear to me as before. We talk about a lot of things, but I think it would be similar if we would be just good friends. At school he might grab my nipple, sit against me or push his leg against mine. Also, once in a pub he grabbed my hand and held it, aswel as just being close. I would just like this all to be real and meant, and that he would think about us the same as I do. He is handsome, sportive and smart, and has a lot of the same interests. My dreamy thoughts are smashed when I think about one waving flag; he has a girlfriend. Not only this, he also mentions her casually to me and I break up every time a bit, I would just want me to be in her spot. We also sometimes talk about their relationship, and I think he is serious about it.

I probably don't have a chance, which got me very demotivated the last half year. What can I do to or be cool with us just being friends, or forget him? I don't know what to do, and the only thing I do is think about him, wanting to be with him.