I like this guy, more than he may like me. But, his best friend is VERY into me, and I am NOT. Help?

I met this guy last semester, and we are both 18. At first I was really nonchalant, and then I got into him. WE sat in cl, and vaguely spoke, then we started talking and texting a lot. We got very close, and I know he has a lot of female friends. However, he always acts so nice with me and I know that he is into me. He tells me all the time how nice I am, attractive, and I have a good heart. He goes out of his way when he doesn't answer right away, in terms of apologizing if I thought it was silent treatment when is was not needed! However, I text him more then he texts me, we hanged out a few times and the first few times I met his band members. They were cool with me, and I enjoyed listening to his band because they are very talented. We started to be fwb (I just got out of a two year relationship, and he got out of a long term relationship too), so we wanted to try this type of relation since we both got heart broken. I KNOW IT WAS A BAD IDEA. Everytime we had , he was always so cold afterwards for a few days.. For example, we were gonna go to school together to register for cles so we can be together, and it never happened. So, we are still close and all, but I ound that he was more into me before we started these "arrangements".. Anyways, so his friend from his band member added me on MSN. He is really not attractive at all, and I felt very uncomfortable befriending his best friend. Sol, I wanted to be nice so we started chatting and I know he jas low sled esteem because he is over weight. So, I tried cheering him up by saying that he has a great personality, and he's attractive. Just for the purpose of boosting his ego. I am not trying to brag, but I am very pure hearted, and I am very attractive. So, I know that he is very infatuated with me. Anyways, so we talked on MSN and he told me that he was attracted to me, and we chatted for an hour. He was very flirtatious, and I was trying NOT to give the wrong signals since I like his friend. He gave me his number, and I gave him mine - HE HAS NO IDEAD THAT I AM FWB WITH HIS FRIEND. The guy I like doesn't know that we chatted so long tonight. I feel like in a triangle or something, and I don't know what to do. Please help me?