Fuck buddy problems HELLLPPPPPPPPPP

Alright, so ive been fucking this guy for about 2 months now on and off. I knew from the beginning it wasnt going to end up anything serious. I ended up sorta falling for this guy and he acts like he has for me too, yet i just found out after we had sex last night after a party he fucked an old fuck buddy 2 nights ago at a party we were both at. I dont know how to feel, im angry and sad but i know i can do so much better but im so hung up on him. He just says and does things like we are something real but then is the same with another girl. I cant be angry because hes not mine and there was never an attachment between us. Hes free to do what he wants and so am I but i still get caught up on him becaude hes everything i want but i cant have him. Ahhhhhh someone help me what am I feeling, what should i do, im so overwhelmed with a mixture of feelings. I cant get him out of my head and he even comes up in alk of my dreams. As soon as he even speaks to me I forget about all the bad and im all caught up in him again. HELPPPPPP