Hi @Chebs and welcome to the forum.
Your story is indeed a touching and heartbreaking one. While I have not lost a parent to dementia myself, I have seen it with friends and extended family and it is indeed a horrible thing. Not much I can say other than that I'm glad you've reached out, and to keep posting. It's a very supportive community and no doubt other members will read and respond in time.
It seems while you're not getting the very necessary support from family, as a carer you might benefit from some carer or at least general professional supports such as counselling - if you haven't sort these already. It's a lot to deal with what you're going through. No one should have to do it alone!
If you need urgent assistance, see Need help now
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