He is holding your life hostage. Dangling the possibility of getting married over your head and blaming you for it not happening. He is toying with you. He says your behavior is the reason he won't propose, and the cycle starts all over again. You are upset because you are wasting your life waiting around on him so it's time to put a stop to that. BUT you have to actually mean it. You can't tell him you're moving out and then back out of that decision when he pretends that he will propose.

Start making plans of where you'll go. Get that lined up, recruit your friends/family to come over and help you move and get out. No need to tell him your plans until the day of the move. Engage a lawyer to get a child custody agreement and move on.