You have to learn to tune out the crying. I had a nine month old like this. Serious separation anxiety with me. I couldn't even go pee.
It took months for him to get comfortable. but he is now the happiest child in my daycare, is my own kids best friend/boyfriend.
I had to train him slowly. First he was allowed to follow me everywhere I went ( would even call him to come with me) but he was on the ground, then when he was comfortable i would leave the room for a couple minutes and call to him if he was crying and let him come find me but I wouldn't pick him up I would talk until he stopped, the periods then got longer and longer until he was comfortable and had made some friends.

You have to like the kid though. Lets be honest, we dont have the patience or understanding we need if we just aren't loving this kid. There was something about this boy I loved even though his screams were PIERCING. I was close to letting him go.

I also had the parents do the same thing at home that I was doing here. continuity is KEY!

But if you just cant stand her, she's better off somewhere else anyways