Should i or should i not leave? need responds immediately! (HELP)?

me & my fiance is leaving together for almost 2 years.we just had baby recently and my baby is about 3 mnths old now.my problem is that when my baby was 1 1/2 mnths i found out that my fiance has been trying to reach his 2 past girlfriend and checking them out and by that time i was 6 almost 7 mnths prgnant.i found this out bec.he had left his email open & forgot to close it but since the first day we live together i always had that feeling thats his hiding something,he kept it pretty long and what pisses me of is that he knows that im carrying his baby & his stil trying to flirt on them on the email.he one time had requested a picture & those ****** bitches send him like a semi nude pics.so it really got in to my nerve! This has been a prblm to us now cz i lost my trust and i dont know what to do.we talk about this & he said he didnt thnk wat he did is harmful or wrong but i know it is. i love him very mch but im jst to posesive since dis hapen.is that wrong?i nid some serious advice!