LAB - I am so saddened to hear that your mother & P's appalling behaviour has affected you so badly.
I know you are in therapy but have you thought of going to Al Anon to help you to deal with this?
I found that after a year of Al Anon I was able to change the way I was reacting to my H's behaviour. I was able to see and understand why he had behaved over the past 5 years in much the same way your mothers P is at the moment - they sound like one and the same person!
H was verbally completely vile and poisonous when he was in a blackout (daily), stopped caring for himself, being sick every day - and sometimes not getting to the loo in time, had lost his job, been in hospital, and was eventually unable to get up at all, so missed dd's 4th birthday.
Meanwhile, I was enabling by balancing all the plates - I was working full time, managing our dd (he became incapable and dangerous), keeping house, caring for sick rellies, doing extra shifts and for what? I could just about deal with the above over the past year, only because of Al Anon. I was hoping that a change in my behaviour would help him to help himself.
And I was then able to see and realise what constituted unnaceptable behaviour and was able to put sensible boundaries in place - ie. if he ever hit me, hit our dd, or behaved appallingly in front of her - once he crossed any of those then that was it.
The end came when he ripped up our wedding photo and smashed an ornament we had bought on honeymoon in front of a hysterical dd and that was enough. I filed for divorce, and I have never looked back.
It hasn't been easy; as far as I was concerned I didn't want to ever break my marriage vows. Even 5 years of unnacceptable behaviour was too much but I had to look at my own part in retaliating, and this last year has been a revelation - if only I had the courage to go to Al Anon earlier on but honestly, it is never too late.
H did hit rock bottom 5/52 ago when my dad died. He as very upset as he was fond of him and went on a massive bender - perfect excuse to do so! The following week he went to AA for the first time and has been about 4 times. Not enough but better than nothing!
I haven't changed my mind, I am still going ahead with the divorce.
I'm only sharing what I've been through personally to give you some idea of how bad it was before I had to call it a day. Some of the people who have posted have been through far worse - if you can, read back.
And all thanks to Lemonstartree who started this thread, because it's been fab to be able to let off steam to people who know exactly what it is you are going through. We have all been there and you are never alone here. We can share what has happened/has/hasn't worked/give advice. And knowing that the support is there if you are desperate - well that is such a comfort.
Please keep posting, LAB.
Hope everyone else is ok too.