Seriously? Wow, what kind of friends do this to their friend in times of suffering? Selfish ones that's what sort! This young woman can still have a normal life as long as she takes her medication, there is absolutely no reason to avoid a person with a medical condition or in a wheelchair. An unpleasant personality will put others off you and that is perfectly valid, but not a medical condition.
If people have a negative reaction to your health issue or disability the problem is them; and not you remember that. Know that you are not the problem; the problem is how selfishly they think and feel. Insecure and immature people, that are not very nice. It has nothing to do with the person that is ill or has a disability. Selfishness is an obnoxious social disability, but who casts selfish people aside? Not like minded individuals; because they need validation from their ilk.
Learn about the person’s medical condition and work around the condition so that the person can still socialise and not miss out. Don't just assume anything, ask the person directly. Learn something about their health issue and learn how to be supportive and be a good friend. Mental health is the biggie here too and people do lose friends; again by assumption. Assumption being the mother of all F***ups!