Need to leave

I guess I just need to vent and let it out. I need to keep reminding myself why I’m going to leave. I’ve been with a man for a year and a half and In that time he has talked to other woman, sexted them, lied to me, ect. We’re supposed to be engaged and I went on his fb an put that he was engaged and he put that his account was hacked.. i think that was the most hurtful thing he’s ever done to me out of everything. We had a daughter in November. He gave me the most best four months of my life. Everything was great we were a happy family. He didn’t do anything behind my back. But that was short lived. He was talking to a girl lied and told her we weren’t together and than told her he’d move in June to be with her.. and what makes this harder is that I have a 8 and 5 year old that love him. I know I need to go. But I love him so much. We live together and I still want to cuddle, kiss, just touch him. And we were acting like everything was okay a day after because it’s easier for me to act like everything is okay than be in a state of severe depression. Worst part is he didn’t even act like he was sorry. He makes me feel like if I walk out that door I’m irreplaceable. So why does a part of me want to stay and fight for us.. I feel so fucking dumb. Why can’t he just want me?