Shadows Sorry you are having a bad week. I was wondering if you think your mother will treat your DB the same as she treated you? I only say this as I have 2 brothers, 1 older, 1 much younger. The older one had his fair share of toxicity from her but was always the golden child. The younger one was mollycoddled as he was the youngest. They both received/witnessed the toxic behaviour but were certainly not on the receiving end of it to the extent that I was.
I remember you I guess as I was posting on here at the same time as you were and what your mother was doing was truly shocking. Parents should want to protect their children and grandchildren but your mother was just unbelievable.
As for her making out that you are mentally unstable to the rest of your family, I know it's hard but try to let it go. Those who are truly close to you and know you well will know the truth. I think this sort of behaviour is a classic narc trait. They rally people around them as if to turn them against you with lies, I think it justifies their behaviour the more people that are on 'their' side and gives them a sense of satisfaction in alienating you.
Shortly after DD1 was born I fell out with my mother. I was living with her and could bare it no more. We then moved in with the IL's (now ex IL's). I can remember being in the room with my MIL whilst she was on the phone to my mother who was trying to convince her that I had PND and was "gone in the head". When my MIL said that I seemed ok to her my mother proceeded to try and convince her that I was putting on an act. Thankfully my MIL just recognised that she was nuts.
Fuzzy You know these people, you know how they will act, what they will do and say to try and reel you back in. You can pre-empt their behaviour and use it to your advantage. As Hissy says "you can get through this". Good luck.
Meerka you are right, nothing is worse than an atmosphere in your own home but right now I don't really classify this as my 'home'. A home would imply that it's ours, our sanctuary to relax and have privacy.
Things actually came to a head yesterday. DH flipped. He received a text from his father whilst at work telling him that MIL had had her op the day before. We had guessed as much but why would they not tell us? Anyway, DH called him and it ended up in a nearly hour long shouting session (DH has sore throat to prove it
) where DH got a lot of things off his chest.
He said that FIL really cannot understand our problem with him
, he doesn't understand why he can't come and go as he pleases in and out of our extension and as per usual his only retaliation was to start on me.
His qualms with me are:
I don't make him cups of tea...when DH pointed out that I am pregnant, suffering with HG, don't drink or make tea anymore as the smell makes me feel sick his reply was to say it wasn't very courteous of me. 
I haven't said hello to him for 2 months.....a total lie but I do keep talking to him to a minimum as I can't fucking stand him
Does that mean he hasn't said hello to me either for 2 months?
I turn on my heels and walk off when one of our neighbours comes around......DH just replied "that's because she can't fucking stand him". God knows when I've even last seen that neighbour as I've been holed up in this house since the start of the Easter holidays which was the beginning of April with being sick and feeling like shit due to the HG.
DH feels he's got it off his chest now but I feel like I want to have my say. DH doesn't want me to and wants me to make a point of saying hello to FIL. I don't want to do that as I feel that FIL will think DH has given me a 'talking' to which he has not. DH just feels that it will pain FIL to have to speak to me.
DH seems to think that once the extension is done FIL won't have any reason to come around anymore and we can grow the hedges, put up big fences and keep ourselves to ourselves. He seems to think that the problem will go away but I don't share his optimism. I know that people like this will just find another way to exercise their controlling behaviour.
During the argument DH had also asked FIL if he would act or had acted like this when they had guests in our house (before we moved in they rented it out as a holiday home)? His reply was "No but you're not guests are you?".
I know this will never end and DH wants me to look at it differently. He says he hates his parents but just see's it as using them to get stuff out of them (he is an only child). I think he's just waiting for them to drop dead so he will inherit everything.......sounds great in theory but they are only in their 50's so I think we've got many more years of this shit to go.
DH has also told me to look at them as sad and pathetic, they are I know but sometimes its just bloody hard.