Can trust be brought back into a marriage when cheating has taken place?

While I was 7 months pregnant my husband was cheating on me. He continued to cheat after our baby was born until I found out and confronted him. When he was confronted he claimed he was not having sex with the other woman. I didn't believe that and a week later he finally admitted to sleeping with the other woman. My husband says he cheated on me because sex was not the way it used to be before I got pregnant. My husband also says it was only a sex thing and he never stopped loving me. I find that hard to believe since he called this woman morning, noon and right before he came home.

My husband now states that he will never cheat again and that I should not dwell on the situation. I love my husband, but it's hard for me not to look at him in a different light and believe what he says. I don't understand how could he cheat while I am giving him what he always wanted a baby, especially since we suffered miscarriages. I want to be able to trust him like I did before but I am not sure it's possible.