Hello, RPW! I have a bit of a dilemma and could use some insight, please. Here's a bit (okay, a lot) of context:

My boyfriend and I are in a very RP, long-term relationship. We take excellent care of each other and have discussed engagement, marriage, and building a family together in the next year or so. His family is wonderful and have very strong RP values; his mother (who is a lovely, traditional Muslim woman) has been nothing short of kind to me and supportive of our relationship.

So here's the thing. My mother is very BP; though she doesn't openly label herself a feminist, her character is much like the stereotypical profile of one: eats junk/doesn't cook, always negative, critical, nagging (toward both me and my father), career-oriented, very strong sense of entitlement, little control of emotions, easily becomes hysterical. We are not (and never have been) close. Others who have met her or know her (friends/family) have asked if she's bipolar. I'm thinking there's a bit of that and/or narcissistic personality disorder at play.

The first time my boyfriend came over to meet my parents for dinner, she talked about my previous failures in life and about herself (work gossip, etc.). At the end of the meal, she continued this while my father and I cleared the table of dishes. As my father loaded the dishwasher, she said to my boyfriend, "Let's see if he's smart enough to figure out how to turn it on." I was horrified and embarrassed that she so nonchalantly disrespected my father like that.

A few weeks ago, the five of us had dinner: my boyfriend, his mother, my parents, and me. This was a huge deal for me and the SO, as it was the first time we were introducing our parents to someone else's parents. His mother was so excited to meet my folks and so was I, despite being nervous about what my mother might say.

When my parents and I arrived, after greeting and introducing everyone to each other, my boyfriend offered my parents wine, to which my mother said, "Oh god, yes, I need a glass. I have to deal with my husband all day." Inside I was bristling with complete rage but kept it together because I wanted everyone to enjoy the evening. Later in the evening, my boyfriend's mother sat next to me and started telling my parents all the things she likes about me and how happy she is that her son and I are together. She finished off by holding my hand and saying, "I love your daughter very much." I was so overwhelmed by her kindness until my mother scoffed and said, "It's only because you don't live with her," before kicking back another glass of wine.

I can't even begin to describe the look of confusion on my boyfriend's mother's face. She ended up taking the high road and said, "Well, thank you for your daughter. She's a gift."

So, naturally, I'm worried about future family encounters. Has anyone dealt with this kind of situation before (with your mother, with families meeting, any of this)? I don't know how to properly communicate to my mother that her behavior reflects poorly on our family without facing an inevitable blow-up from her end. Any of your advice or experience would be greatly appreciated. Thank you in advance for reading all of this and for providing a place to discuss things of this nature. :)