why is it so hard to come out of a toxic relationship

For sometime now I have known that my partner has been cheating. At first I confronted him and he managed to convince me that the said girl was a relative ' but when a girl knows she knows'. I knew something was definitely going on from when I was pregnant about 38 weeks. he didn't want to touch me and would sometime s literally removed my hands from him when I touched him or looked the other side of the bed. after baby's arrival he would sometimes come home late and refuse to touch the baby no matter how much she cried and I was doing something or just tired.in my culture one isn't supposed to touch a baby when they have been intimate with another person who is not the mother unless they take a shower. So recently I found out that the other girl is still in contact with him actively anyway I think that the girl might be pregnant because of something he asked me. I really want to leave but I still don't have the strength and I also want to talk to talk to someone but am not ready.

what pains me that I have been found with low blood pressure and UTI almost thrice after these and feel am drawing away from my faith. is it always really this hard to leave