How to handle a parent who's going to do whatever they want and thinks everything is about them??

Nanabell, your profile says you are taking care of both parents while working full time. I think you are nearing burn-out for carrying such an immense load by yourself. Your dad sounds like he is maybe sliding into dementia now too, or he may have an untreated UTI (which often doesn't have any other symptoms in the elderly other than behavior/personality changes and confusion). He would need to have a test and can be treated with antibiotics, if this is the case.

You need relief, obviously. Can we assume you are their durable PoA? Has your dad ever been given a cognitive exam by a doctor? Do your parents have enough financial means to pay for in-home help until you can transition them into a nursing home?

You are not obligated to provide their care until they die, even if that's what they want and expect. No one can be involuntarily "assumed" into this type of commitment. No one will doubt you love your parents if you make other arrangements for them. The caregiving arrangement needs to work for all parties, or it doesn't work at all. An amazing number of people on this forum have been (and currently are) in your same shoes and will provide support and insight. If you can provide the extra info requested, it will help. Thanks!