Anger about not going to church

My dad is 75 and in the mid-stage of Alzheimer's. He lived in a different state until 14 months ago when he made the decision to be closer as I am his caregiver & POA. No other surviving family lived close. What had been nice since his diagnosis was that he was able to convey that he knew it was time for the next "step" in this journey. He adjusted to the move better than anticipated (his previous AL was not managing his medication properly) and particpated in daily activities, outings and was socially active again.

Up until June, he was fluidly mobile. Taking him to church wasn't an issue because he could dress, bath and get into the vehicle easily. He has made a significant progression though and no longer understands he needs to bath or even what clothes are for. He had been able to read the notes I wrote on his whiteboard, but no longer reads much at all. On a medical outing a month ago, he fell on his behind. He didn't trip, he just fell back. He was not hurt, no broken bones, and didn't hit his head. When we arrived back at his facility, we talked about until using a walker or wheelchair, it had reached a point of being unsafe for me to take him places, but especially church. He flat out refused to consider a walker or wheelchair. He didn't remember falling 45 minutes prior.

I informed the staff of what had happened so they could check for a UTI or a possible medication to be the cause of the balance issue. None were found to be the cause. At my next visit, I reiterated that I did not feel safe about taking him places, but especially church. I told him I can bring church to him by watching online with him. He nodded. In the past week and half, he has gotten angry and verbally abusive to staff when I don't appear on Sunday to pick him up. (I hate this disease.) He can't remember what clothing is for or the days of the week, but somehow suddenly is aware I didn't get him on a Sunday?!) He is now filled with anger in seeing me when I do come 2-3 times a week and tells me I have left him there and I don't care about him at all. It's heartbreaking and difficult to remain calm and not cry in front of him. I know it's the disease. Do any of you have advice on how long this adjustment could take or am I now in a stage where anger will be the norm?