Handling a hospital stay for the less demented parent?

I've just brought my mom home after a couple of days in the hospital for observation for a low blood pressure crisis. I'm wondering how any of you have handled this situation. Mom was fine in the end; she is suffering from a milder dementia than Dad, so she fully understood what was happening and why she was there. On the other hand, Dad has mid-stage Alzheimer's. He seemed fine at first, just wanted to know how he could get in touch and find out how she was doing, so I left lots of large-print notes around his apartment, saying which room she was in and the phone number of the hospital. I even put one in his pocket. He's in assisted living, so I didn't stay with him the first night, figuring he'd be fine with the notes and being able to call on the phone to find out how she was. The caregivers told me in the morning that he had gotten very upset in the night, not knowing why she was gone; by morning, when I came to pick him up to go and see her, he was asking me "how long she was going to be in town" and he was flabbergasted when I said she actually lives with him and has lived with him for sixty years! He was very happy to see her at the hospital, but when it came time to go, he became belligerent with me and the staff and insisted he wouldn't leave without her, even though the doctor wanted her to be under observation for another day. We were able to extract him with the help of the hospital security and staff (it was heartbreaking to have to do that, and Dad kept asking why we were "treating him like a bad guy").

I decided to stay with him that night, but it became impossible when he started believing in a fabrication that his mind had come up with to explain her absence - he thought he had abandoned her at a construction site where he had gone to work. (There's a building under construction next door to their ALF, and I think that may be where he got that idea ...) Anyway, he was very upset with himself for "leaving her there" and I couldn't convince him that she was just at the hospital and that she would be home the next day. He wouldn't go to sleep, he stayed agitated, and at one point he became physically violent with me and threatened to punch me in the face because I wouldn't let him leave the bedroom (hoping against hope that he'd just go back to bed -- foolish, I know!) That was when I'd had enough, and decided to go home for my own sanity and let the professionals handle the situation. (The caregivers agreed and said they thought it was better that way for him, too, since having me there was not part of his routine.) Fortunately the next day she was released from the hospital, so I was able to just bring her home without having to take him there again, but the whole thing left me utterly exhausted and very sad. I never thought that having one of my parents in the hospital for a minor incident would be so trying. (I even begged her doctor to get her a private room the second night, because I knew it would be bad if Dad couldn't stay with her - unfortunately that wasn't possible, and the hospital's rules wouldn't allow him to take the empty bed next to hers, because their rules for that ward didn't allow mixing genders in a shared room.) I am thinking that I should line up some professional caregivers other than the workers at the ALF to stay with him all night should this happen again -- maybe someone trained to work with agitated Alzheimer's patients, who knows how to calm and redirect them. I was hopeless at it, and I usually handle communicating with him pretty well. It just was too much for me. Any advice from folks who've been there and done that?