I think you should tell your mom immediately. She is your mother and it is her job to protect you, no matter what she has going on in other areas of her life. Someone with that kind of temper and the blatant leering could easily escalate to rape. I don't think the answer is leaving the house, unless you want to leave and then pull your mom aside and say, "This is why."

This dirtbag has raised you since you were 5 years old. Your mom deserves to know what kind of creep she is married to and you have a right to be safe in your mom's home.