I remember a time years ago, when my MIL went to a fabric store, and bought bolts of fabric. (My MIL had an illness...bi-polar). She was one of the best seamstress around, but when she had flair ups of this, she would go on a buying spree and not really have anything special to make. It was a horrible life to live as I watched her when she was well vs. when she would get sick. People made fun of her and were so rude to her. I took the bolts of fabric back to the store for her as she wasn't able to hardly remember where she got them.
As she aged, her bi-polar illness got worse. She was in a nursing home for 10 years and when she would be in a "manic" state, she would be driven to do everything. She could crochet anything without a pattern, but when she would be in one of these states, whatever she tried didn't come out right. I remember the CNA's making fun of her. It broke our hearts because if they had known this lady, it would have meant the world of difference in the way she was treated.
So you did the right thing in not being rude to her, because until we walk in another person's shoes, we don't know what they are going thru.
I suffer from severe depression and I have been told that I act as if I am better than they, when it is really I am so depressed I can't interact with people. I just keep quite.