Have to leave new dog for 3 days, suggestions?

I have to go away for 3 days, and I always leave my dogs home w/a sitter. I have a new dog, a 3lb abused "pocket pet" chihuahua. She's very shy still, not aggressive but still learning a new life. (we're teaching her real dog habits, its amazing to see her learn!) But, I'm not sure if I should leave her at home with the others, she's hasn't met anyone new, and doesn't have trust for much. I'm concerned of her doing potties outside and being afraid to come in, which ends up in a scary situation for a dog like her. And her not pottying at all from fear. (that happened when we first got her) I'm concerned about taking her to a friends house, because it'll be another new place, new face new sounds... etc. She's made a LOT of progress and I would hate for her to be set back, or learn a new fear. I'm really conflicted on what I should do for her, and what the best option would be. So I am here looking for suggestions. All I've gotten so far is oh jeeze... I don't know. LOL That doesn't help me much!

Thanks in advance :)