The worst responses I got were “Oh, wow” and “I’m sorry to hear that”. Then I never heard from either one again.
The best one was my boss: “I’m sorry. I don’t really know anything about MS. What can you tell me about it?”
I don’t mind people asking me questions or even offering unsolicited advice, but do NOT tell me that I HAVE to do this or that and it’ll make me all better.
Don’t treat me like I’m fragile, but recognize that I know what I can and can’t do. Strolling slowly beside me is fine if we’re walking, but don’t hover over me unless I’m actively having balance and coordination issues.
We’re all different and have different emotional triggers, so go with your gut and what you know about your friend. Stay in touch even if she doesn’t call or text you as often as before. Don’t make a big deal out of her having to cancel plans at the last minute. If she can no longer do a popular activity, find something else that you can do together. Understand that her abilities might change on a dime. If her friendship really matters to you, you’ll find ways to work through this with her.