I don't see why your mum should subject herself to abuse. Dementia or no dementia, I'm sorry, but she didn't sign up for being treated with abuse and aggression. Perhaps she needs to remove herself. If he is capable of acting acceptably, then there is no reason for her to take this kind of treatment. Sure, everyone says "it's not the person, it's the disease" but there are no awards for being a martyr are there?
If he's calmer and happier without her, and she's calmer and happier without him, is there even a question.
I guess she needs to ask herself some tough questions and look after herself, not only her husband.
I was in that position myself and took the advice given by zeeeb actually. My mum and sister both passed some years ago so there is just me left to cope with my dad, other than my husband and grown up children. My dad is a complete and absolute beast to me since onset of dementia yet prior to that, we were incredibly close, good friends, did everything together. Now he simply wants to rule my life. Yells at me for going on holiday, for not visiting him in the CH enough (I used to go 5 days a week!!), he would phone me up to 20 times a day and if I didnt answer, he would leave an abusive voicemail..... nothing I did was good enough and he just became more vile with each week.
Yet staff said he was lovely to them, was always normal with Dr, district nurses etc..... everyone but me!!
In the end, I realised, I had to take action, especially when he started doing the same to one of my daughters because we have our own lives to live and it was genuinely affecting my health and well being and causing such distress.
We took his mobile phone off him and we cut down the visits to 3 a week between us. I always go with somebody else, and in fact, since his call to my daughter, nobody goes alone.
I thought this would all make him steam more, but actually, the past couple of visits, he has been more relaxed, more pleasant and more..... pleased, I think, to see us....
almost as though he realises now that his behaviour has alienated us/me and he has to 'behave'.
I am learning slowly not to feel guilty for withdrawing. No, nobody should have to suffer that kind of abuse and I dont think my dad in his 'right mind' would expect me to. Maybe your mum can take a step back and accept that though it is the illness doing this, she has to look after herself because truthfully, there isn't much she can do now for your poor dad.
I do feel for her, though, it really isn't easy to take that step back, but I promsise, it does get easier.
Big hugs for both of you.
Trisha