Serious relationship problem?

my last ex girl friend who i was with for 3 and a half year's say's she loves me an that she thinks about me from time to time the problem was is that i met another girl on my job and i messed around with her and she said that i got her pregnant only to find out that that wasn't true so i told my ex and she was waiting to see the result's then we broke communication because of a dispute between her and the girl since then i've talked to her and she has gotten over the past but when we talked about getting back together she seemed happy but then she didn't so i'm trying to figure out weather i should just teller her how i feel witch she already knows or just leave it alone? i think about it when there's nothin else to think about or when talking to other women but i just can't stop thinking about it we both love each other when we were together we looked at each other as husband and wife