Agression, combative, critical.

I am the care give to my mother who has some dementia. In home health care comes in several times a week to check vitals. I administer meds, cook, clean, transport, etc. She is critical of everything I do. She demeans me to home health staff, neighbors and a few friends that she has maintained. She blames me any difficulty in the home and when I attempt to make tasks for her easier she accuses me of calling her, "Insane". I put an extra trash can in the bath room for to put used diapers in as opposed to her attempting to flush and cause plumbing issues. This caused a "Hissy fit".
I am exhausted and emotionally worn out. I am attempting to find a daytime elder care site to give her some other activities and socialization. She has basically one friend that has attempted to stay in contact. She is critical and argumentative with others and has alienated many. There are very few who want to be in her company for any length of time.
I any one has any suggestions on how to respond or avoid being screamed at on a daily basis, I'll be happy to hear.