Does anyone have experience with sending a loved one to a nursing home for respite care?

Mom will be going into a nursing home for respite care for 5 days. I have to go out of town, so I cannot care for her then (I am the main caregiver). I am so worried about how she will react, though. I am expecting the rest of my family to go visit her, hoping to ease some of her anxiety (that I expect she will have). I don't know what to tell her about going, other than to tell her it will be a vacation for her. She is 94 and is showing some signs of dementia. Will sending her for respite care make things worse? I won't know if there is a bed available until a few days ahead of time. So, if there isn't one available, I will have to hire more in-home care to cover the time I am usually there. It seems she has an issue when new people come to the house. I feel like I am between a rock and a hard place.... Any suggestions? What can I expect when she gets home?