At times, Dino (the cat) acts very mean and aggressive, and he hates people (but he loves me, comes into my lap when I'm there, at least as long Reinhold isn't in the same room).
THAT says it all!!! Their own animals are afraid of him!!

Reinhold has a big problem with animals, loving and respecting them. I wouldn't be at all surprized if he treats your mother the same way. He sounds like a control freak to me. Some women's self-esteem is so low, they settle for guys like him. They feel they are NOTHING without a man in their life. How do I know??? I USED to be one of those women. Years later I realized that a woman without a man is like a fish without a bicycle.

I feel sorry for your mother. But I would stick to your guns. It ISN'T about Lily. It's about Reinhold respecting your wishes when he's in YOUR home.