What is he really saying when he says he just cant come back and make it work with you?

He is saying "goodbye" ... men will reach an impass situation where they no longer have the drive to make the relationship work. It seems there is lots of hurt feelings in this relationship - and those hurts have existed much too long to be repaired anymore - this is always a painful experience to endure, but if it's meant to be, it shall ... maybe this is the time for professional counseling.