Welcome to the forum and sorry to hear about the reason that brought you here. I think most of us will have had similar experiences at one time or other with our loved ones, and for those of us limited to public transport it's not as if you can just pull over and deal with the situation in private. Mind you, sometimes a third party can have more success calming situations than we can ourselves.
Delusional episodes are horrible and they've definitely limited what I'm prepared to try to do with my mother; I don't even dare take her into town for shopping trips any more, she'd often get upset on the bus and refuse to get off without a major scene that delayed the driver. We have, however, recently got onto the client list of a local independent carer who's prepared to try all sorts of outings with us. It's opening the world up a bit for us again, and although it's now one of our biggest financial outlays, it's worth it.
The world does, inevitably, shrink as the dementia straightjacket tightens on a family. But, with help, some freedom can be regained. And although I may be suffering some kind of psychological disorder, once your wings have been clipped, the chances to flap them again -- even a little -- feel so much more precious.
Having said that, when life was getting a bit much for me in my working days in Kent I would finish a night shift, get on a train as soon as I could, and go sit on Hastings beach for a couple of hours before I had to go back and get some sleep before the next shift. I do miss that kind of freedom a lot, but now I have the freedom to play my guitar almost as much as I want (ie as long as Mum taps her feet), become a tat expert thanks to Bargain Hunt, and to type semi-useful stuff into internet forums. And I've learned to enjoy gardening as a meditative process, so I'm grateful to my mother's dementia for teaching me that.
What I'm saying, in a clumsy kind of way, is that sometimes shrinking horizons allow us to focus on things closer to home, things which can bring us just as much pleasure. Sometimes I feel like I'm in a zoo rather than roaming the plains, but at least there's only one lion to worry about here and she's currently asleep after refusing her 'morning' pills for the umpteenth time.
PS If none of this makes sense, I blame it on a cocktail of stress and lack of sleep!