I was playing a heads up match with my brother for 5 dollars and we got it all in pre-flop while he was short-stacked. I had J10s and he had A2o The board ran out 10, 3, 3, 3, 3. I was pretty noticeably annoyed at the run out because the win was so close but the river gave him the pot. He started laughing so hard because he thought he had gotten very lucky to chop the pot. I started laughing extremely hard with him because he had not realized he won the pot. We played a few hands with the chopped money but the I felt bad so I decided to tell him that he actually won the pot and I would give him the chip stack he would have had from won from that pot and we would resume play from where would have been after that hand. Keep in mind in those few hands I had actually gotten him really short so this deal would give him more chips. He immediately was furious and said he doesn't play with cheaters, and was crying about how poor my etiquette was. He refused to play and took his money.
Obviously the money is not a big deal, and I should have told him immediately if I was going to at all. My question is if I hadn't told him would that be cheating, bad etiquette or neither?