My aging mother has paranoid delusions after a stroke. What do I do?

Hello, my mom is 67 years old and has had 3 mini strokes. The first TIA I believe occurred approximately around age 60 however there is no solid confirmation of the exact time, it's just a guess based on behaviour changes that were noticed around that time. At the time my brother was getting married and my mom started exhibiting some very strange and out of character behaviour however we had no idea at the time what was going on with her. The 2nd TIA was during a vacation at which time she took a very hard fall. She said she tripped. But many odd and concerning things were noticed after this as well and it wasn't until months later and many conversations with others about it that I figured out what was going on. I talked to her about this and encouraged her to see a doctor at which time it was confirmed she definitely had 2 mini strokes. Over the years she has become extremely paranoid. For me, it was difficult to know what was going on and who to believe. My mom became very accusatory of my brother around a number of subjects, one being the claim that he stole money from her that he promised to invest. To me this seemed out of character for him to do something like this however I was never there to see the interactions when these things "happened". Consequently my mom later cut my brother out of her life and her will. I was still unsure who to believe because I had seen my brother react very strongly towards my mom on many occasions as well, but also now believe this was partially because these confrontations and strange behaviours were becoming an embarrassment to him around his new wife and her family. I thought with the termination of their relationship (which I DID try for a year to talk her out of) would at least bring some peace. But I have since come to realize that my mom is suffering from paranoid delusions. She absolutely believes that my brother is spying on her, trying to get her money, have her thrown into a home etc. This may not sound crazy to some since there are people that would do this to a senior and initially I trusted her and took steps to help protect her. But the accusations get worse and worse with time. She has stated that my brother's wife, who is a nurse, is trying to access my mom's health information so that they can plot to have her put away in a home. She has stated that she is sure my brother put a tracking device in the wheels on her car. She has stated that my brother sent his (also elderly) father-in-law to follow her and spy on her because she ran into him twice in stores that she was in. She has stated that my brother (who also lives 2 hours away from her) is recording her phone calls and that she knows for certain this is true because she saw a van parked outside her house and looked in the window and saw what she believes was a large recording device on the front seat. She says there was a wire she found outside her home that "later disappeared" after she called the police about the van outside her home. And most recently she visited me and parked her car a block away and when asked why she told me that during a previous visit she got into her car and realized that the odometer had 3000 more kms on it then the day before. I clarified what she was saying by asking if she believed someone got into her car, drove it around for 3000 kms and re-parked it in the same spot and she told me no. She believed someone with a computer (implying my brother) had connected to her car and changed the odometer remotely, either that or the dealership had rolled back the odometer at some point and it had just jumped forward again. She confirmed this was all possible on google. She also believes my brother faked his cancer. All of this is getting so confusing and exhaustive for me. I don't know what to do anymore. I sometimes forget that these things are stroke related because she can seem totally herself in every other way and it can sometimes be months between mention of these paranoid accusations. They used to sound almost believable but now they just get worse with time. Recently she admitted to me that she had the 3rd mini stroke in which she was unable to speak. But says her doctor said it was just a "blip" and she is fine. She also had calcification of a heart valve which she claims is also drastically improved since she started taking supplements for it. However, she waited until a year later to tell me about either of these things. We had a trip planned together and she didn't want me to cancel the trip so she hid this from me. She has also mentioned selling her house because she believes it is close to the return of Jesus Christ and the end of the world and she thinks she needs to prepare. I try to go along with some of her discussions but discourage anything drastic by saying things like "it could be another 50 years before Jesus returns so you'd better wait". I don't know what to do anymore. It's getting bad. Help! What do I do??