Really need some advise :(!!!

So me and my husband got married in May and we officially got together in February after being friends for a while. He had sex with a girl last year January and she got pregnant. She called him in June to tell him that her baby father of her first child is the dad. So we stopped worrying. Any ways am 7 months pregnant with my first child. And he told me yesterday that the girl called him 2 weeks ago to tell him that he is the dad! I am completely heartbroken and just cannot stop crying ! I thought this was our first child together our little family now am finding out he has a 3 month of child with another woman... Anyway I've packed up all my stuffed and moved back to my mums ... I've even given back my wedding ring . This is not the life I wanted and I am just so upset I don't know what to do . I hate him and this whole situation... This pregnancy has been so difficult for me and now I just don't want him at the birth, all I keep saying is that he should just go be with his other family and leave us alone . What do I do ? :( I feel like I really can't get over something like this... I just don't want nothing do with him and his other child and I don't want him in my life neither :(