I've been dating a guy for three years, even lived with him. Sharing him with his mother. I've never seen anything like it in my life. She'll call at 3:00 in the morning, throw a tantrum, and he'll run to her. She can threaten him that if he doesn't show up, she'll poison herself. She's in her mid-50s, he's 35. Whoever he's been with before me, she's against it. She insults me, she talks shit about me. And now it's scary, she's cursing me and my daughter. He left her to live with me, everything was fine. He went to visit, came back, glassy-eyed, yelling and throwing. What to do, I do not know ... 
#life #history #interesting

Consider seeking professional help for both of you. Boundaries with his mother seem crucial. It might also be helpful to involve a therapist to address these dynamics and ensure your safety and well-being.