First time dating !

Okay I’m 19 I’ve recently started dating this year. I work with this guy who was a bit older than me like 23 we worked together and was friends and thangs. Then we started dating and getting serious then boom I found out he had a kid. Okay in the beginning I trusted him and all of a sudden idk I just felt he wasn’t over his bm. He told me multiple times that he was over her and that nothing was going on between them and he would tell me he hated her. Come to find out he sleeping in the same bed as someone you hate ? I left about 2 months ago to continue school and we decided to do long distance before all this happened. I called his phone on his birthday to find out I was blocked so I called restricted to also find out a girl had his phone !! I was furious. I’m just confused on how someone say they love you but treats you so bad