sometimes I get really angry at my friends
It seems like theres a story there. why do you still get angry at them?
They always make jokes about my past. They still make fun of me for not able to get to the university.
Your anger is justifiable. It's wrong on their part to mock you constantly.
Oh I am not angry anymore, I realized that university is stupid.
You should explain to them how you feel about university and their mocking. THey might be open to listening to you and may even realize their mistakes.