How can we handle my mother's move into a senior living facility when she keeps forgetting she agreed to go?

My mother has dementia, after many talks about moving into a Senior living place my mom finally decided to move there. We talked to a realtor to get a price on her home, talked about what auctioner to use, went and looked at rooms apt. she could choose and afford, had several conversations over several days in a row. She finally decided on a room, put a down payment on the room to save it till we could move her in. She wrote the check. Then sat down with the advisors from the Senior place, she signed the contract and wrote another check for the first month. I called her later in the day to remind her we would be coming to take some of her stuff to her new home, she was up beat and fine with it. Then when we showed up to move her she didn't know why we were there and threw a fit and said she wasn't moving. Accused me of taking it all over, she didn't want to do it and I did all of it without her knowing. She really needs to move into a place where she has someone around, I can't always be there. I don't know what to do or how to handle this. Please help!!!