Thought I'd share, as I've seen many a post on here about difficult FMILs.
Those of you who have been following my FMIL dramas know what a saga it's been and how challenging and unsupportive FMIL has been.
A little while ago FH put his foot down (somewhat prompted by me saying I had hit the point where I was just unwilling to be in the same room with her because I didn't want to put myself in a position to be treated rudely and risk saying something I'd regret and never be able to take back). It was horrid, he had some awful exchanges from her after calling her out on her behaviour but he put it all out in the open and very firmly told her she was being disrespectful and needed to stop. She didn't apologise, but did agree to draw a line under it and start fresh.
Anyway we went to visit on Sunday and I was incredibly nervous. HOWEVER, she was very obviously making a huge effort to be nice to me the entire day!!!!!!
I did go in very much ready to "kill her with kindness" as my mum put it, so I think that probably helped as I could have gone in a bit stand off-ish and with my guard up, but FH's painful but necessary calling out clearly did the trick.
So for anyone else with FMIL woes, hang in there, don't let yourself get walked all over and let FH fight the battle because it can get better 
