(Have NC for this as its a bit outing!)
DH keeps clashing with his DM. When they have a drink shit hits the fan in an epic screaming, crying, showdown. Once sober she pretends it hasn't happened and carries on as normal. 
DH is not faultless - he is goady AF, but he is very reasonable about listening to her PoV. She plays the victim as she feels her charmed life baggage is worse than anyone elses, and trust me, it isn't. DH calls her out on this and she flips out and says something spiteful and hurtful - largely about he lives his life and how we are raising DCs, which I take (because I'm pretty sure its meant) as a personal attack. She is selfish and often makes comments that we should be doing x,y and z as its better for her, despite it making life harder for me/DCs. With DH she is hysterical and confrontational, with me she is very passive aggressive and back stabbing.
Her mental health at times is very delicate, so how do I deal with this? (Going NC is not an option)Do I bite my lip and post horror stories about her on Mumsnet for the next 30 years
or is there anything I can do to smooth this over?