I need some advice on sex in my relationship!

My semi-boyfriend and I have been dating on and off for a few years.

We were really really happy until his mom died a year ago, his parents didn't have a functional relationship so he doesn't really understand how to act around me. Long story short he is immature a lot of the time and I'm praying he grows out of it. His dad was mostly a jerk to and around his mom so he learned to not care what I think of his actions.

From what I described he probably sounds like a terrible guy, but he's really not when we have long talks and he understands that some of the things he says AROUND me and NOT to me make me question his character.

I told you about his background because this behavior is worrying me, I don't want to have sex with him again (we used to have sex) until I know somethings will change. I'm very emotionally uncomfortable having sex with him when I know if he doesn't grow out of this I can't handle it anymore.

I'm not questioning whether I should be with him, I'm hoping things will improve, I'm just wondering if I should hold off on sex till he is more mature and ready for a more serious relationship. We are both 18, so he's not some grown immature man. We are both young and still allowed to be immature.

Thanks and I'm looking forward to hearing what you think!

P.s. Sorry, but I'm stressing these points; there is no question that he loves me. I know we have more growing up to do. He's very sweet when not around his jerk friends or inappropriate father.