Very very complicated situation... awkward to... help?!?

Ok so i met this guy at work in oct and since then he caught my eye. Anyways we have been texing for about two months and we went out on our first date about 3 weeks ago. Here is the catch. He has a gf... three weeks ago when we went out she was in asia somewhere were she had been for the past 3 months. Anyways, so we went out on the date and after that we were inseparable.... texting all day and we would spend afternoons together just watching tv and lounging around. NOTHING EVER HAPPENED (no ) just kissed... sweet romantic kisses. Ok so his gf came back 2 weeks ago and is planning and is leaving back to asia in less than a month for good. These two weeks have been so hard!! i feel horrible for what i did to the girl... but i really think i found the man for me. I mean i even broke up with my ex boyfriend of two years. Not for the new guy but i just didnt love him. The new guy tells me how much he misses me anytime he can get... e-mails... text messages... whatever. Always leaves