Blind 79-year-old father w/ undiagnosed dementia and more. Living at home w/ someone not fit to care for him. What are my options?

I’m now the only next of kin to my blind and disabled father with undiagnosed dementia. He lives in my family childhood home. There’s a second cousin who was moved in after his last lengthy hospitalization where it was determined he couldn’t live in his home alone, per his needs. Before my sister passed, he begged us as a dying wish to let him pass in his home no matter what had to be done. Now she’s gone. With him being blind, many problems have occurred with the individual who was entrusted to move in with free housing in exchange for a small list of daily responsibilities/tasks, including administration of daily necessary medication. His/my home now looks like a frat house and I have a laundry list of spontaneous irrational decisions causing him to fall backward from over excursion, fall behind with his bills I was managing, etc. Her communication skills are horrific now and my mother and I recently just found the extent of how much she’s been taking advantage of the entire situation. Including finances. He shared that he’s no longer comfortable to talk on the phone because “she knows too much." She listens to all his conversations. I can’t even talk to my dad anymore. He sounds like a stranger on the phone and is being influenced easily because of his dementia. His daily needs are not met. I live 1hr 10mins north of him in NJ. I'm desperately in need a therapist at this point, because even group forums help with sharing and venting but my own life and relationship of 10yrs is now heavily impacted by the toxic situation. My baby sister passed last year in February and I haven’t even been able to grieve her properly. Almost immediately after her passing, his health declined severely. It was already in decline prior to her death. Now it all lies on me. He was too sick and in isolation to have documents signed. Tomorrow I’m hoping to get his POA done. But he’s being told by ppl that it means that I call the shots on everything. He’s now being reluctant when last week he was more than willing. Jokingly said "I’m waiting on you." I need help to get him on Medicaid too. He only has Medicare and it’s not enough. His bills have gone up bc the extra ppl in/out the house are not paying anything. He told my mom under a blanket, that things aren’t right but he won’t and can’t say anything because he’s afraid. That he has to live with this/these individuals when we leave. He fears the treatment or reactions to simple conversations over legitimate concerns. Respite care isn’t even the word. I need to get someone else in the house that will take the situation serious, respect the nice home and me and my father’s wishes. She called a week ago to say she came home and he was just gone! A person he thinks is his “buddy” picked him up and took him out the house without a care in the world nor telling anyone. This person is a bad actor in all aspects. My father shut off his online banking which prevents me from paying his bills. His “caretaker” secretly sold his ride on lawnmower worth $1500, for $300 then took $100 as a tip. Shes moved her father into the house and put my stuff in the basement. My father claims he was told he must pay rent. But it’s been months now. I need him diagnosed formally. He can’t recall much from that outing. He got new cards and the same day had a accident and they were found in the sink.I need to regain control of my home and father’s care.

I'm 3 semesters away from graduating from Polytechnic University at 40-years-old. I had to stop taking classes. I’ve sacrificed so much to keep him in his home. If he wasn’t blind and could see the condition of the home he built he’d have a heart attack. His moods quickly change, and today I offered to get him back on track and all he was concerned with was taking his money out the bank. Again I don’t have a POA yet. What am I supposed to do about any of this? Giving her notice, she’ll complain I fired her and he’ll say no u can stay. Yet has complaints all the time.