Husband teaching sons to fight?

[Janet]

My husband Rick and I have 12 year old twin boys (Bob and Ben).Rick is there stepdad,the biological father is a deadbeat. They are great kids and do well in school.There only problem is that they both stutter.They've been going to speech therapy for years and it has helped,but the stutter really hinders them socially.The other kids make fun of them and bully them.Last year Rick decided to make the boys have more confidence.Every night after school they have an excercise routine they go through and then he and his best friend I guess try to teach them to box and basic fighting moves.Now after a year I am afraid that they taught my boys too much,because whenever someone starts to make fun of them, my boys immediately get in their face and challenge them.I am not exxagerating when I say they've been in over 10 fights this school year.While Rick tells them to never fight unless necessary,I can tell he's proud they stand tall now.How can I stop the fighting but keep their confidence up?