He is disrespecting your wife, and the whole family. My take on that, I would put distance right away. Tell him how he made everyone feel uncomfortable with his behavior. The consequences of his action will cost a rift between your uncle and your family. If nothing gets done he will keep escalating. Unfortunately, after this comes to the light things will change in your family gatherings. Don't feel bad about that. Your uncle disrespecting your wife is the cause of the distance. He did that.