Help me please! Im angry, hurt, and confused:( but im also happy!:)?

Hey, Im 15 and my crush is 18, my crush and I start talking back in December and he got the feeling Iiked him and he started to like me back, one day after we came close he was in the library doing college stuff and he said sit by me and he was like you should text me and I was all excited and stuff. �But after he was done with the college stuff he left the library and my friend was like he was cute and I was like yeah back off tho, and I made the misyake of telling my crush she said that and my crush said whats her name and I gave her his name and he DIDNT even know who she was but he added her on FB and after they got to know eachother they start dating and I was PISSED but they broke up like 3 weeks laterand me and this girl are not even friends anymore, I hate her guts! But my crush is liking me alot more but I dont want to go down this road again and on top of that he is going to college, what should I do? We dont talk at all anymore but like I said he still likes me and alot of other girls:(