sam, I'm glad you went home for the holidays and spent some time w/your family. You needed the break. As for your poor dogs, I'm so sorry to see she was acting like an irresponsible teenager. Since the dogs went to emergency care...what was wrong w/them?
If I were in your situation, I would have a sit down chat w/her upon your return and thank her for trying to take care of things while you were gone, but in the future, your dogs are never to go to that woman's place again, i.e., that you will find a dog sitter who is reliable and does not drink and forget the pups. You have to let her know how you feel about this situation...it was not okay to do what she did. She was in charge of taking care of them, hence, she should have checked on them, fed them and if she wanted to go out and party later, then so be it. Are you going to have to pay the vet bill? I wouldn't offer to pay any of it since she was left in charge of the pups.
You have to be the one to decide whether you want a boundary in place about the feeding of the dogs when you are commuting from work. You have to decide if you are comfortable w/her being in your home when you are not there...I, personally wouldn't be, but maybe you don't have a problem w/her nosing around your stuff. You'll have to make sure that any of your paperwork, etc., is locked up on hidden because you don't know if she is snooping or not. Again, only you can make a decision on this one.
As for the anger, it is a stage they go through, but keep in mind, they bounce around from anger, replay, depression, etc. They never completely stay in one stage. Their stages are very much like the grieving stages that we experience. And, yes, they can be angry at the color of the moon and it will have nothing to do w/us, but we will be the ones to get the lashing.
Try to enjoy the rest of the holiday and travel safely home.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.