Does the other father know what he did ? I mean the bruises ? Perhaps he didn’t realised that he put too much pressuire on his harms.
You should ask this father a meeting at the school with the principal, the teacher, your son and you, and take the pictures and papers from the hospital to show him. IMHO, you should tell this person that :
- If he have a problem about what’s happen in the school, he should go to speak with the teacher, that will speak to the parents if needed, and not to come directly in front of a little boy like what his did (and not to come to the house of the parent and break everything like what you were thinking also).
- He should not let his anger talk like what he did.
- He should not talk to young kids as if he was in front of an adult in a bar.
- Some writting on a hand made by a kid to another kid (this may happen often, and it is often like a game for them, not a way to make an offense) is not comparable to what he did.
(optional) - Your son said that it is not him that wrote on the hand of his daughter.
You should ask him :
- to make some public excuse to your son, where he should explain why he should not have done what he did. Ask him to write an excuse letter that will be publicly displayed somewhere in the school (the principal could accept this, probably), this may be displayed in a place where nobody go but at least it might remain in the mind of the other father.
- to do something symbolic that will stand longer than 1 day, so it will not be quickly forgot. Also think about something that could bring friendship between the parents and children (use your imagination … ask them to invit you to a friendly dinner in their home or you will sue him, for example
).
If you acheive all of this, your son will feel safer and will forget this bad event, and this kind of problem will not happen again.