How to calm my anxiety?

Try anti anxiety meds and antidepressants from your doctor. It’s time to be frank and admit you need help. It’s amazing how well they work.

With dementia at play, it's necessary to tell mom whatever story she needs to hear to keep her calm. Telling her that her mother is dead is obviously not going to keep her calm, as you'll have to KEEP telling her that same story 1000x and have her upset each time. Tell her that her mother is living in Florida where it's warmer, or she's off visiting a relative, or whatever 'fiblet' suits you at the moment. I know it's stressful b/c I had to do that with my own mother for a LONG time when her dementia ramped up and she was constantly asking me where HER parents were? It caused me a lot of anxiety, especially at first, coming up with stories and excuses which kept me off my feet! Coming up with a story at the spur of the moment was tough! So I just kept saying 'grandma was living in Florida b/c it's too cold in Colorado for a woman her age.' Which was true, b/c grandma would have been 137 years old at the time! LOL.

Don't feel 'guilty' b/c your brother chose to take mom in to care for her; you are doing a kind thing by going over there 4 days a week as it is. Don't feel guilty, either, for feeling stressed out b/c dementia causes stress for ALL loved ones. It's a horrible situation you're all dealing with, God knows, I dealt with it for 5+ years with my mother, so I know. She lived in Memory Care for the past nearly 3 years, and I suggest that's what you look into yourself, not straight up AL, but Memory Care AL which will be a great solution for ALL concerned.

Best of luck

The anxiety is familiar to most of us who did any caregiving at all, whether in home, or separated by miles attempting to handle financial things, pay bills, oversee sales and repairs. It is a normal reaction. If you feel you need some help with in it terms of a medication you can take when things are at their worst, one that will not impair your functioning, do speak with your doctor (I sure had to).
You are taking the right steps. You and your brother seem cognizant that you cannot keep up the caregiving in-home and you are checking on facilities.
I am uncertain what facilities you are checking, but it is important to be honest with them about your Mom's capabilities and needs. She may have progressed beyond what can be handled in ALF where most seniors are well enough to function in large part for themselves with minimal care.
I sure wish you good luck.

It seems you are overwhelmed. It's an extremely difficult situation, anxiety is normal. It seems you have a good relationship with your brother-can the two of you share your thoughts and anxious moments? You might find some reliefe in doing this and hearing how your brother is affected and not feel so alone in all of this. Therapy, if possible is great. Mindfulness and being kind to your mind works well for me.
I try to keep all my anxiety going during the day, don't ignore it. In two online support groups, one social worker, several friends who have been through this, two online dementia classes, writing in a journal, writing here, are the ways I deal with anxiety during the day. Because, I need to rest and sleep as well as I can at night and if the racing thoughts get revved up then-"it can wait 'til morning to deal with them".

I would be looking for memory care if you are not already.

my mom has hallucinations as well , started just a number of months ago. When my mom starts , I mentally tell myself to breathe, patience, basically mentally step back from it. I tell myself her brain is broken. That’s how I deal with it. It does no good to argue with her that their are no dead animals on the roof across the street, nor a man with a gun living in an igloo in the yard…

Also I suggest taking her to the doctor and make them aware ahead of the visit that she is experiencing this.

I wish you peace with all this