first thing to do is take a few deep breaths,calm down and start looking into some volunteer people in your area. I too have my dementia mother 24/7, just gave up my life in NY to take care of her and my father who just passed 3 wks ago.
Even if it for a few hours,take care of yourself and try not to get overwhelmed. Write in a journal,just short notes on your day, Good and bad. I does help.
You are giving the gift of love, and you are a better person for it.
My heart is with you also. PS-I have numerous years of training in this field-did it for a living-but when its your own, and entirely different story. Just remember--Its not her fault