What the heck do I do?

Theres this guy named alex and like Ive known him for about two years and Ive liked him for a long time. ALOT. I've began hanging out with him mostly everyday and we've become like best friends and we have started to trust eachother and I think Ive fallen for him. Now, I don't think he knows this and we've been sort of... Friends with benefits. About a week ago we had and it was my first time. Ever since I have been totally and completely pissed at him and I don't even know why. And I already have a boyfriend. And there's this guy that won't stop slobbering all over me. And on top of all this, I think I may be bi. I don't want to be bi. I think that maybe me having with alex was me trying to cover up my feelings for girls. Then Alex keeps asking me if Im bi and it's pissing me off because its embarring and I don't know how he found out but I don't want him to know. And just now my sister called me and said that she was pissed at me for being pissed at alex because now he's crying in front of everyone cause he's in love with me which is what Ive wanted for a long time but Im too pissed to even look at him and I don't even know why. Then my sister and my best friend started calling me a ***** and saying that alex doesnt deserve this cause he only wants to be with me. I told her that if he had wanted to be with me that he should have said yes six months ago when I asked him out and he said no. Then she started cussing me out and I hung up. Then I started sobbing uncontrolably. Now I just want to know what to do. Please help me.