I got cheated on

I have been talking to this guy for over a year. I just found out he slept with another woman two months ago. asked her to marry and built a family. I was completely unaware of it. I’m genuinely heartbroken and disappointed. I put up with his mental abuse for so long. This is the message he sent me this morning. “ Let's get engaged I don't like when people say you are young there's plenty of fish and the sea but you will never ever ever freaking compare I don't care about anything else but you”

He keeps telling me to wait and give him a month. I mentally checked myself out, but I’m afraid he won’t stop until he gets what he wants.