Cheating husband

My husband and I have one been married 11 months. About 3 months ago I found out about him cheating. I caught him three different times before I actually got solid information that was real proof. I needed someone to talk to it about it so I  turned to his mom (stupid decision, but let me explain). My mom passed away in 2009 so I have no woman figure to talk to about these things. Her advice really bothered me because she said that I should start treating him so good that he forgets to wonder if the grass is greener on the other side. This hurt my feelings because I don't believe I should have to compete for my own husband. Well the other day I found more info in his phone that he is on a dating site for hookups, and he's talking to another woman who he calls his friend. She sent him a picture in her bikini. But he deleted the stream of texts. Also I'm currently pregnant. I just don't know what to do anymore. I feel like I have no one to turn to. I feel so worthless. Why does this keep happening to me?! Any advice on this? My husband claims to still be in love with me. But I don't believe him anymore.