BUGS BUGS BUGS

Bugs in the toliet, bugs on the wall, bugs falling on me in the shower, bugs in the sink, bugs on the counter. "MY bathroom is full of bugs." I am not sure how to convince my mother that she doesn't have a bathroom full of bugs.  SEE BUGS ON MY SOCKS.. no bugs on your socks that is lint. It won't even come off your socks, " THAT'S right the bugs are holding on." She scrubbed her toliet and said she got all the bugs, they form a ring in the toliet. I told her there wasn't bugs in there it was just a ring that forms in the toliet. She stuck her hand down in the water and up the hole where everything goes and rubbed and rubbed. I lost my cool, I yelled at her what in the hell are you doing? Why would you put your hand in that toliet and reach up there? she said she was stirring up the bugs.  she showed me her light switch that is on the wall beside her toliet. "SEE BUGS!" no bugs mom... Do I mention what it is? She turns over her booster seat on her toliet and says " SEE BUGS!" Do I mention what it is?
Okay, yes I do, it's poop, and yes it's nasty and yes it's terrible, but she has poop on the seat, poop on the light switch, poop on the sink in spots.  She also has a large chocolate bar in her bathroom and it has chocolate crumbles that fall on the sink. She has very bad eyesight and can't distinquish what she is looking at when I show her.  She doesn't believe that it is poop on anything, even when I wet toliet paper and scrub it off the seat and off the light switch and show her.
Is this dementia making her delusional? She has gone on about bugs for 3 months now and there are a few little bugs but they aren't forming a ring in her toliet and holding on to each other to be scrubbed out...
I wish I could handle this better, but I didn't handle it well.