I want to stop this sinful act.
The reason this happens is because you got hurt: emotionally and possibly physically. The one who had to protect and cherish you has committed something he had no business doing. Now you really need help, otherwise your marriage would be at risk. Please, consult your pastor at a local church (if you attend one) or seek help of wise women or psychologists. Read articles online on how to overcome the past and leave it behind. Pray and God would direct you to the help you need so much.