David I dont know what I can say that others already havent said.Just say in my own way...
can say that I quit my job at hotel because I didnt want to be the person who called in late or called to not come in at all. I quit because my face pain couldnt allow me to go threw day in a comfortable approprate professional like manner. I also think you should not feel bad or quilty at all for speaking about her. It seems you have reached to help her and you have helped her hang on to her job covering for her and picking up her slack, putting up with her . But then the line must be drawn at some point or you become and enabler. And one must at sometime stand on her two feet and take responsibility for herself and not expect other to handle her responsibilities. Do not feel guilty she knows better then that... it seems to be a way for her to controll and try to lay guilty but it dose not lie with you it lies with her. She isnt in touch with ethics and fair treatment of her co workers . The guilt is her not yours David.
I hope your work (and your train of thought on yourself) get fastly improved all for the better!
Many blessing on you
PEACE
BMW