Questions: Flirting

Okay so, I'm a white guy and I ran into an old friend from my school days. We were never that close, but I partied with him sometimes, so he invited me to his house for some drinks and to meet his wife. I reluctantly went, but whatever. For context, he's a white guy too and she's from the Philippines. So from the moment that I met her I was shocked by how beautiful she is. She's also really kind, smart and an excellent wife and mother.
My friend on the other hand is an asshole. He criticizes her constantly and for no good reason. Once we started drinking I lost my composure and I definitely told her how beautiful she is and what an amazing wife she is. I felt kind of bad for the feelings I was developing for her so I just decided to stay away from them. Jump ahead a few months later and that guy is texting me again. He wants to have drinks and this time he picks me up, drives me to their house and basically forces me to spend the night. I'm reluctant about it, but secretly excited to see her again.
So there I am drinking with him, listening to him critisizing her like usual, but this time I start interrupting him, sticking up for her and telling her how incredible she is right in front of him.
I could tell it irritated him but I don't care. In private he tells me how stupid she is, and in private she tells me what an asshole he is.
I'm stuck in the middle, he's a big scary guy and I'm falling in love with her.
How do I handle this situation?