What would you do if your son got in a fight in high school?

The reason my son gave for getting in a fight for high school is because a boy joking around called his mom ( me ) a prostitute. Basically said the money was under the pillow and such and was calling my son pu**y . The calling of names went on all last year and part of this year... the talking about his mother happened once the other day, and my son spear tackled him and punched him a couple times in the gut. The other kid never retaliated at all. What / how should I punish him ? I sorta feel he defended my honor.