Husband with dementia (diagnosed by our PCP) is having strange anger spells. Any advice?

We have night home helpers (very expensive!) because the worst he does happens at night -- sundowning. He has had two people with whom he got close. One of them had a tragedy at home and had to stop working. So yesterday I was told that a new one, very nice and experienced, would be taking the 3 days the other one took. I told them he objects to strong scents and conversation unless he starts it and she was informed of this. So at about 7:30 she called me (my husband and I live a few small houses apart, thank goodness) and said he got very angry at her, told her she was wearing perfume (she wasn't) and ordered her to leave, go home immediately. I talked to him a bit and said this meant I (who right now am quite sick with some kind of stomach flu) would have to go to his house and take care of him. I calmed him down by saying that she seemed very nice and intelligent (he agreed) and if it was so bad, couldn't she go upstairs and take a shower? He began to mellow. I talked to her about the shower idea and she said she was familiar with the "invented anger object" in people with dementia. We talked over his pill schedule (he yelled in the background "NO TALKING!" About 10 minutes later I called him (partly because I was so angry myself, although I know an angry response from the spouse does NOT work) and he said cheerfully that everything was all right. I told him that lately his demands have been embarrassing to me and cruel to both me and anyone else in the picture. I asked if he still wanted her to go and he cheerfully said "No, we worked things out." (I think he had demanded that she get no closer to him than across the the room--difficult to give meds, water, and so on) and probably she said that she would take a shower with his OWN soap if he demanded it and certainly would before she comes the next day. I, still angry, said that his display when she arrived was not acceptable. He responded with what has become his standard excuse for these things: "Oh, I was just joking around with her."
We haven't been able to get a diagnosis on TYPE of dementia except for "dementia and cognitive decline" from our PCP. (He does take Seroquil at night to calm him down). Does this kind of "anger demonstration" happen with a specific type of dementia? During the day his main problem is that his short-term memory is just GONE. And does anyone have suggestions about how to deal with these little "shows"? Frequently they involve a demand to change something that either CAN'T be changed or would be hugely expensive and involve a lot of work to get in place. I'm 73 and have some chronic illnesses. Dealing with a hospital stay of 3 weeks (serious infection) that brought sundowning to the fore (I got about 5 hours at home to sleep for 3 weeks) and then trying to take care of him myself (he absolutely refuses to leave his home) drove me into a near collapse. What kind of future can I expect, does anyone know?