Cheater please help 😥😭

I find out last year my husband had cheated on me with his ex who also has his child. It hate me soon bad that I was crying myself to sleep. I decided to forgive him because I love him and feel I put so much into out marriage I can't just throw it all away. A year later I'm now having a baby we both planned but the thing is I'm still so hurt about what he did. I hate him for detorying our marriage we had a really happy relationship. I asked him why he did it but he tells me he don't know why. Now I'm pregnant I feel like I hate him more all I think about is what he did. I lost my dad brother and nearly got killed and I got rape on holiday after my dad passed. all in the space of 2 years then he topped if off by cheating all I doing is crying. I don't want to lose my baby because I'm feeling so unhappy I really need some advice. I feel I'm losing who I was and I don't know how to get her back. Please help