He cheated, I moved back for my son but I am extremely unhappy! heeeeeeeelp!?

my husband cheated on me again but this time the girl called the cops saying he d her. it was some skank who thought he would give her money to shut her up. But anyways our marriage went down the drain. I trusted him to a point because i thought before he made a mistake but then i realized he is never gonna change. But he is a great father to our 2 year old son. I left him 2 months ago but came back because I thought it would be easier for me to go to school and plan for my future if he could look after our son sometimes and pay for a few things for him. I know it doesnt sound that great but I am 21 years old and he is 40 and he has money to help me. my son is very happy seeing his dad and they do many activities together but I am not happy. I hate living in the same house as him he disgusts me and always makes ual advances. I cry everyday asking myself why I came back but I know its to improve my future. If I move he will always bother me and if he stops supporting our son then I dont know if I can afford to live here. what should I do? my friend said i shouldnt depend on him but its like what can i do when i need his help and he is wiling to give it. I want to get a divorce but that will limit his ways of helping his son because then he will not be able to become american. or should i just move to a completely different city and start over alone with my son? i just enrolled in school though..theres this low income housing i found but i dont know if I can see him happy I want him to suffer...like i did...