This isn't easy, and I feel for you and the family, and also for the poor dog.
Distemper is serious. She may even die, though there is a chance she will recover. I personally haven't known a dog with Distemper, or a Distemper survivor, so hope you receive more answers from someone who has had this experience.
Yes, it's possible if she survives, she may bear some neurological scars but I have heard such things can vary in severity.
Beware also, because I have also hear a dog with Distemper can appear to get better, yet relapse a few days later.
What should you do? I can't say. I know you must feel so sad and at your wits end. I also can't say what I would do, if I were in your position. And this is a really difficult dilemma.
The decision involves your Heart, your compassion, but also your family life and finances (if she would need on-going medical care) If either of the latter just won't work, then sadly adopting her won't work.
If she would need round-the-clock observation for instance, and there is no-one in the house all day....if your finances won't support it.
And not everyone is cut out to be a 24/7 veterinary nurse.
You have to consider those things.
But if you want to stand by her thick or thin, for better or worse, then learn all you can about Distemper survivors and what to expect, so that you can adapt.
And remember -some cases may have a better prognosis than others.
Right now, she is probably better off receiving veterinary care. I am sure they will let you know if or when she would be fit enough to return to your home anyway
I send you my kindest wishes, and blessings for your dog.
I'm sorry I couldn't be of more help.