I dont play as much console games as I used to (resorted to PC now partially coz I like some PC orientated games), one of the reasons I play less is that you did always get that annoying kid, who had to be the "toughest" in the lobby (not to mention their lame ability to crack your mums jokes). Atleast with the PC I dont run into these kids!! And for the games I do play which envolve lobbys, I just mute the voice chat, join a call on skype with a friend, get some music in the background and chil…
You have answered your own question about whether or not to quit. It's always health first my friend! Never put your job (especially mcdonalds) before your health, healths a priorioty! Also if its affecting your studys, i'd let them know. Even try get your working hours reduced.
I was bullied back when I was 13, at the start of my school years. Luckily for me I had an older brother, he sorted the whole problem out. Fair to say though, the reason I was bullied was complete stupidity.