I frequently hear you advise callers they have to stand up to their parents. This advice generally is followed by a silence and then a gulp from the caller. I want to share my experience.
Years ago, my mom and dad visited me and my new husband in our home. I don't remember the exact remark my dad made, but I do recall that it was intended to be derogatory toward my husband. I took a deep breath, turned to my dad and said "I can't allow you to insult my husband in our home. You have to leave now. If you can never do that again, you are welcome anytime. Otherwise, don't call me and don't come back." The room went silent. My mom looked like a bomb had just been deployed. My dad started to bluster and tell me everything from him that would be discontinued if I didn't apologize to him. I stood up, repeated my remarks and started him out the door. He blustered all the way and mom looked shell-shocked, even as they drove away.
It took about a week for my dad, who NEVER apologized for anything to call with an apology and a request to start over. We accepted.
Until he died, my dad never truly liked my husband but he always treated him with respect.