How to handle a situation with mom’s boyfriend

Back story. I came out to visit her in Cali. This is day one of my month long trip. She’s elderly and lives with a younger man. Long story short... he’s been drinking! He pretended to fall and grabbed a handful my ass. I almost stabbed him with my damn fork.

I wonder if my mom knew exactly what happened with his “fall”, because my mood changed and she looked a little worn out inside.

He also walked out of his bathroom slowly naked and looking at me, then slowly walked backwards into his bathroom. I just ran straight into my room with my mom and daughter.

What the hell do I do with this man? I’m trying to keep my cool. He plays WAY TO DAMN MUCH. My moms out here alone. I have my own family in another state. Shes not going to leave Cali. She’s been suspecting him of cheating. He works with celebrities and rich women. My is a beautiful, and not exactly wealthy woman. She doesn’t look her age, but this man is out of control. I don’t want to break her heart. And! I don’t want to get into with this weirdo.

What do I do?