room for wrath

Romans 12:19 Do not take revenge, my friends, but leave room for God's wrath, for it is written: "It is mine to avenge: I will repay," says the Lord.

Recently, Caden got a bit bullied. A boy in his Sunday School class said "I don't like you. You're ugly". Then he apparently followed Caden around, bit his face, and then somehow they got into a spitting match. This was all from Caden's perspective - so I don't know exactly how it started, and I can't vouch for complete accuracy.
Caden told us this on our way home. I was ticked off at the boy, at the teachers for not telling me, at this boy's parents, and at Caden, for spitting back. And I was really pained that this sort of encounter happened when he is only 4! Makes me wonder how much worse it will get?
Don't misunderstand, I'm really not hoping the Lord will punish this other 4 year-old (maybe a little discipline would be in order). But I found it amazing how angry I got. It seems much easier to allow God to take over when something happens to me, than when something happens to my child.
On a Much different scale, God had to watch people on the earth treat Jesus poorly throughout his life, and of course, watch his death on the cross. And Yet, there was no revenge to be had. This was following through with The Plan. I just cannot imagine.