Why are my friend's being soo sensitive?

earlier a few of my friends were at my house and i was in the backyard playing basketball with my friend and my lil bro (he's 12) and the 2 girls were watching. since there was 3 of us we just played 2 on 1, both of them vs me, since neither of them are that good that im awesome. anyway in the middle of the game i tripped over my brother's leg and fell and they were laughing at me and it was embarassing. so i got mad and took the ball and threw it as hard as i could at my brother's face from like 2 feet away and he started crying. and my friends were like aw dude that's f'd up and then it was awkward and a few minutes later they left. wtf its between and my bro, what difference does it make to them? it's my brother's fault anyway that he's a crybaby. do i have stupid friends or what?