I am no psychologist, but this sounds to me like an abusive relationship. Why are you putting up with this crap? Because she brings you such joy? Because you have a child together?

Having been abused and cheated on for 12 years, I would be packing my damn bags if I were you. Noone deserves to have to live like you are currently living. There are plenty of people out there who will not treat you like dirt. Please advocate for yourself.