Datin a guy for 3 months, but the love of your life wants you back? helpp ):?

I've been dating this guy for about 3 months and he is a nice guy but kinda controlling always on my back about something. But now the amazing boy I fell in love with is back in my life and we talk and see each other everyday. We want to be together but I'm dating him && he also has a girlfriend? Im not sure what too do. I have never felt this way about anyone but him... ):