Cheating boyfriends: please do not judge me

My boyfriend and I been together for some years and I found out he cheated on me with his ex from her... And there was almost a baby in the picture... Anyways he begged me to stay in a relationship with him and because I love him I stayed but I am however resentful towards the idea that he was with someone as despicable as she is. It also hurt that he lied. Anyway, I met this other guy who looks better than my boyfriend and is really into me. I do want to make my relationship work with my boyfriend but this I start noticing that I am only talking to this fellow to make my boyfriend jealous. How can I get over the fact he cheated, lied, and held this secret in for a year to make our relationship stronger?