Question aobout forgiveness and the bible?

i know that one of the laws is to forgive but what if it was so WRONG and HURTFUL and BAD do you stay with the person that did it to you and risk it? i will give you my example my common law partner cheated on me with my 14 year old sister (at the time) he was 24 he was on drugs. He dosent do the heavy drugs anymore and he stays home but mentions how i keep him in a box like he dosent like his life and i suspect that there has been more times with other people recently as well am i supposed to forgive that according to whats right? sorry my question is probably jumbled and all over the place but i type what im thinking im having a hard time with this i feel like we are using each other he isusing me for my wifely services and im using himfor a place to live and to make sure i dont lose my kids he could be spiteful like that... yes we have kids and are not married i know thats bad ... :0( i just feel he will do it again ...so do i forgive?