What should I dob

I have been with my so for 5 years and we have a daughter together but we both have cheated on each other he has done it more then my one time i know what I didn't we wrong but I always has that feeling that he is talking to other woman I ask him and he tells me he not should I stay with him or broke it off we are supposed to get married we just have not set a date and i want my daughter to have a family unlike me