Think alot of people may have missed your 'question' as it got pushed down fast.
You did the right thing taking the dog out of that place, and I also think you are doing the right thing in not keeping her, she sounds like she needs alot of care and attention, one to one. Sam would probably be more jealous of her than if you got a healthy puppy, as these dogs take more time to sort out than a pup sometimes. You also have to think about ALL your 'family' and if everyone is so upset including the cat it is really not fair on anyone.
At least you have a friend who can take her on, so you can keep track of her that way.
We had someone came to class with a collie, she got on so well with that dog she thought she would get him a friend. The second collie was a real pain and a totally different nature to the first, it ended up nearly breaking her marriage up, her first dog hated it, her husband hated it (he was not really into dogs)!! She eventually rehomed the second dog, then had to start and sort out the first dog again as all the trauma had started it off with bad habits!
Collies can be so different in nature, you can get really sweet easy ones, then you can get totally mental ones. We have alot near me that are bred on farms, totally workaholic and manic in a pet home.
Try and get a dog that fits your household if you still want a friend for Sam, whatever the breed!
I am sure you will find the perfect dog, but in the meantime at least you have helped this little bitch. (just being groomed has probably made her feel 100% better!)
Good luck