I'm pregnant and my boyfried was cheating on me?

im17 almost 18 and 7 1/2 months pregnant and i found out my boyfriend was cheating on me, he has cheated on me for a long time bu just with hoes. And he says he hasnt but i know hehas. how can he lie to me he all wasys sys he loves me and everything all thistime i thought i was the only one and i wasnt i told him it was over but i miss him so much the only thing that keeps me from going back is i remember all the times he's cheated on me. and after i have the baby im goingto fat i cant be fat if am i know i will be depressed i have to loss it fast