Hello
@Glitzy and welcome to Talking Point
That must be very upsetting foe you ((((hugs)))))
Im going to go for a scatter-gun response as I dont know the whole situation, so please ignore stuff that doesnt apply.
What is she like when you are not there? So many people have found their PWD (Person with dementia) to say how much they hate their care home, but discover that they are perfectly happy when they are not there! It is often the case that seeing their relatives will will trigger off the "want to go home" loop. If the carers are saying that she is OK at other times see if you can observe her before she sees you, to reasure yourself that she is OK.
How often are you visiting? If you are going every day then although she may not remember you visiting, she could well be remembering the
emotions and continue to feel upset next time she sees you. It becomes a negative feedback system. Could you cut back the visiting - maybe go away for a weeks holiday, which might cut the loop (and would also make you feel better)?
When you visit, dont spend the whole time trying to comfort her, and definitely dont try to reason with her. Logic and reasoning disappear with dementia and constantly trying to comfort her will, perversely, simply reinforce the whole problem in her mind.
Never cry in front of her. Go in with a bright breezy isnt-this-all-very-nice attitude and a little treat for her - she may reject it
at the time, but will probably accept it after you have gone! When you realise that she is getting upset dont comfort her, distract her. Get her a cup of tea and a biscuit. take her for a walk around the garden, bring some photos with you that she might like to see, or disappear off to the loo (I went to the loo a lot when mum first went into her care home). Dont stay for long anyway and if, despite all your efforts, your mum gets upset, get a carer to find "something important" for your mum to do and just go.
It could be just a phase. The nastiness often appears at mid-stage dementia. With mum this happened
before she went into her care home; she accused me of all sorts and told me I was an evil daughter who cared nothing for her. This continued for a while once she went into her care home, but then the paranoia went away and she became settled and happy.
Im sure you will find that it will eventually pass.