it is hard to take tho, I do get your point as to why you are offended MCD. so, YANBU to be offended, but YABU to call her ignorant.
thoughtless yes, but not ignorant, not really.
the thing is, every one of us here can be offended by things that every person says to us every day, if we really wanted to. My mother is schizophrenic, has been in a home all my life, I was raised first in care and then by my aunt, and thru my life I have had countless other things happen to me.
Now, people calling other people 'mental', now that could offend me, but 99.9% of the time they are not meaning it offensively, just as a joke/a wind-up/a throw-a-way comment....
and then other people could go on about psycho's, and rate them all as bad, which, going on my posting name, I could also take offensively......but they are not meaning it maliciously. (well, I would hope not).
things like being racist, or saying dreadful things about the disabled, yes, they are offensive, and should be taken as such, especially if said in a nasty tone accompanied by other agressive language.
but what you describe, the way your friend spoke.......no, she wasn;t meaning it in a harmfull or malicious way, she was just commenting on how hard she was cleaning, yes in a thoughtless way considering your own issues with OCD, but not nasty in any way.
In fact, I would bet she would be MORTIFIED if she thought that her comment had upset yu this much....I know that if I were your friend, I would be.....and I do have issues in that regard when I am highly stressed.
I hope you don't take it all to heart tho, and brew about it all night. You are stronger than that.