<human>: I could really use some advice here. 
My mother (55) constantly belittles my stepfather (60) in front of our family. It's always made me (and everyone else) very uncomfortable, but now with my first baby (and their first grandchild) on the way, I'm afraid that if I don't take steps to help this problem, it will continue and not be a loving environment to expose my child to.

They've been married for 20 years. Stepdad's an alcoholic and can be a jerk and annoying sometimes, but is mostly respectful to her when we're around. Mom is sensitive and very negative about life in general, but especially men. She complains about him a LOT, but especially if he's around, along the lines of:
* he's bipolar (although he's never been diagnosed by a professional)
* he needs to be on Prozac (never prescribed)
* he never enjoys anything
* he never helps out with this
* he never takes me here

Often, when the family's together, he makes comments about how beautiful she is. Her response (ALWAYS) is, "Oh he never says things like that when we're alone. He's just putting on for you". 

He NEVER responds to her negative comments, just sits there quietly.

I feel like the things she says to him are emasculating, and if she's unhappy with how she's being treated, saying things like this in front of her family (that he loves and respects), is not helpful and will only make him behave worse. 

Like I said, my mother is very sensitive and prone to feeling victimized. I'm afraid that if I try to point out how nasty she's being, she will think I'm siding with him, and the whole world will be against her. 

I love them both dearly and hate to see them so unhappy. Any suggestions?

Can you give me a shortened version of the text?
<bot>: Short of moving far away, what do you do when one parent belittles the other to the point of running everyone else out of the room?