Is it right to "ruin" a minors life to teach them a lesson

My son is a freshman and high school has been really hard this year. He has two friends and is a really shy kid. My daughter is a junior and extremely outgoing and has a lot of friends. We've dealt with people picking on my son. He's gotten picked on because people have said he's gay. He's never come out as anything so if he is he is. If he's not he's not. I've put him in therapy. He was doing really well in therapy. Then last weekend he went with his friends to the library. They were sitting down and some older kids from his school. Seniors. Were messing with them. Then left. They game back and dumped a bucket full of stuff from the porta potty at the park near by all over my child's head. He got covered in human waste and started to cry and one of his friends ended up punching both the guy AND a girl in the face for it. I got called to pick him up. My husband helped him clean up and I called the police. The police said what they did was assault and battery and harassment. I said I wanted to press every charge I could on these kids. My mom(who was never around when I was a kid) things it's too much and they're kids who shouldn't have their whole lives ruined. She was never around for me or my brother's so she knows nothing about protecting her kids. She things it's a dumb prank. I think they committed a crime. They should be punished and I'm planning to go to court over it.