Not very hopeful that there are any easy solutions to this one... but the relationship between DH and my mother has always been tense and now it's just about hit rock bottom.
DH is quite highly strung, also has bipolar and the medication can make him very grumpy at times. We get through these times and actually have a very close and loving relationship although when he is not well we do have some very big rows (no violence).
My mother and I are quite close and she had a disastrous violent marriage which has left her seriously scarred. The problem is that when DH is stressed about anything he can address me quite sharply - raised voice, telling me not to nag etc. I let this go (maybe I am nagging, and I know it will pass). But when he does this in front of my mother she always reacts to "defend" me and the two of them end up having a shouting match. This happened yesterday in front of SIL and DS - eventually I told them both that they had to shut up as it was upsetting me - told Mum she could not see the whole relationhip and should not judge on just these comments, told DH he should not make others hear him speaking to me in that way.
Now Mum is saying she has made a huge mistake in moving to be near us (she moved 6 months ago and I'm very dependent on her help with childcare for DS and 7 months' pg with DD)that "I need to do something about this" and shouldn't put her through hearing him speak to me like this. This is not the first such incident but I think things have come to a head now.
Sorry to go on for so long but I don't know who's in the right any more...