How wrong is this? Please Help!! My son and my BF's son were both at our house during the summer!!?

Now both are used to being the only kids, they are 7 and 9! they ended up fighting all summer and it was ridiculous! for the most part we had to keep them apart! I am not sure what it was all about! Now, back in June we were fed up with all of the fighting and everything. They came in one evening and the 7 y/o was crying again.. We told them to fight, if they were gonna fight, then fight and get it over with so we wont have to deal with this problem again. so the 7y/o goes and hits the 9y/o in the arm, and he did nothing back, we ended up spliting them up again and not thinking anything of it, no probs since then. til today, nothing had been brought up. I get a phone call from my kids counselor at school saying they are pressing child abuse charges because my son told her what happend. and he exagerated it BIG TIME! He told her his nose was busted etc. He didnt even have a mark, nor was he hit in the face!! I tought that was the way you handled kids fighting! we did not touch them