I'm going to tell my mom that I'm going to move out if she doesn't leave her husband
Why do you want her to leave her husband?
She married to an asshole without thinking about it so she should be the one to fix her mistake
I understand your frustration, but it's wrong to try to dictate the terms of your mom's marriage. You should just let her be happy.
But he's so annoying, and I hate him.
I'm sorry that you find him annoying, but that is your issue, not hers. If she's happy then you really have no right to tell her to leave him. It might be best if you try to ignore him.