Welcome to the forum @therealstacy!

I understand your situation all too well, unfortunately. Both the lack of friends due to trust issues, and questioning if a friendship is healthy.

Regarding your friend's hypercriticalness, is this fairly new behavior or a tendency from the start? The answer's useful. We all have stressful times when irritability shows its head. I have! It's a shame when the anger becomes directed at others, unfairly or overly harshly. Could your friend be too stressed? If so, you might mention the change, that it concerns you, and that you are suffering some consequences and may need to step away, if it continues. For your well-being. But that you do care!

If your friend is hypercritical by nature, welcome to the club of people that know such types. I do. It is tough changing them. When I was younger, I received such criticism silently. As I've aged, I try to halt it on the spot more readily. I'm sure she is farrrrrr from perfect. A critical nature is an example. Do speak up before quitting her. Consider rehearsing such conversations beforehand to ensure they're "constructive" or "concerned" rather than confrontational. If she angers from it anyway, well, you did your best.