The fact they haven’t sent any more fat jokes says something, but before that they sounded like they were being a bit hypocritical. They really should apologise rather than say nothing. I’m being generous here but maybe they feel awkward about it? It’s not very mature of them, in any case.
I’m guessing when the other friends said they’ve never seen her being rude/judgmental, it might be that she’s just never been that way towards them? That doesn’t make how she talks to you ok, of course. Everyone deserves to be treated with dignity, no matter how they look.