Your situation is really scary! Gary sounds like a psycho! It sounds like he has a double personality. Something in his head isn't right. Gary needs therapy and medication.

I think it would be fair to end the relationship over it. You don't want to get stuck with Gary. And you don't want to be someone who abuses you in front of your children. Being with someone who has mental health troubles can be exhausting. And you already have a full plate with the kids, chores, and work. You have to look out for yourself.

By the sound of Gary's rant, it sounds like he doesn't want to be a parent. Someone who wants to parent wouldn't bitch about helping out with kids. Or helping out around the house to make things easier.