I do like women actually, I am a girly girl and have more female friends than male friends and enjoy company of both. However, for me, there has always been less drama and bitchiness surrounding my male friends. I can't say why, there just has.
If one of my friends was deliberately being nasty and rude to me, then of course, I would cease the friendship. Everyone has the right to be friends with whomever they chose for whatever reason. Now we may not know the full story, but if the OP is telling the truth and she has just mentioned uni a few times in conversation etc and relayed a couple of old stories, it seems like a massive overreaction to unfriend and block her without an explanation first.
None of us know the full story, however I wouldn't ditch any of my friends because I was sensitive to a couple of comments they made, I'd like to think I'm a better friend and a nicer person than that. And if I WAS going to do so, I would speak to them about it first, no it wouldn't change the outcome if I was insistent on ditching them, but it may make them more aware in future with other friendships. This girl has done this, but only when the OP asked for an explanation which I just think is a bit cruel and nasty.
Men, IME (before you go getting all het up) tend to be more black and white and straight down the line, if someone says something that has annoyed them, made them feel uncomfortable etc, they will say there and then 'You're bang out of line' and go from there...women, again IME don't so much, they sit and stew over it, make it a big drama and then there's a massive falling out.