Looking for some advice from the professionals out there!

A little background....This is my second year operating a daycare out of my home. I have two dcg, 2 and 18 months and two young boys of my own. One of my dcg is fantastic, sweet, easy going, a real delight and I'm grateful to have found such a wonderful family.

2 year old dcg on the other hand is turning out to be a nightmare. Most days she is anti social, screams her head off if any of the other kids come near her, she's miserable, I sometimes have to separate her from the others so she can play alone and she is just difficult to be around. Example: the button on her pants popped open while she was playing one morning and she began screaming hysterically. i calmed her down, explained she needs to stop crying and ask for help as i wont tolerate the screaming but am happy to help. Her parents are fully aware of how she behaves and don't quite know what to do either as she is the same at home and her mother frequently apologizes for the 'hysteria' as she calls it. I have tried hard to work with them and ensure their daughter is happy in my home but find I'm not enjoying caring for this child (feel horrible admitting this) and the other kids tell me they don't like her.

My thought process...I know some kids are sensitive I don't want to fault the child or the parents if she is just really sensitive. The parents are good ppl, dcg has her moments when she is sweet, she comes 3 days a week- the PT schedule is hard on her. She was my very first client... So, I'm torn between being loyal to them knowing the disruption it would cause them, and maintaining my sanity and putting my family first as my oldest tells me he doesn't like dcg because she cries all the time. I also feel like a failure because I can't seem to get it right with this one but I also worry that she's miserable and needs to be somewhere else, like a licensed facility with staff who are properly trained to deal with a child like her.

Comments? Suggestions? Just as a side not... She was off for 2 weeks at Christmas and everyone was much happier in her absence, myself included.