Mom doesn't know I have a boyfriend

So I'm 19, he's 23. We've have been together for a year, and we broke up because for a few months because he couldn't decide if he was ready for a relationship and begged me to come back, later asking if I would be his girlfriend and I said yes. We are currently planning to get engaged.

Now when we had been together for about 4-5 months we had a huge fight, like a really bad one, and I told my mom and she wanted me to leave him. She thinks I did, no idea I'm with him and doesn't like him.

He has fixed all of his issues and I can tell truly loves me. I know I need to tell my mom, as i think he plans to propose soon. I'm so terrified though. She's very passive aggressive and will pressure me to end things or just be plan rude. I know my boyfriend is very scared to meet her. I need help figuring out how to tell her.