Almost Outplayed

I raise under the gun to 5 which folds to the bb who calls. I have jack 10 of hearts. The flop is 8 9 3 all diamonds. Small blind checks i decide to check. Turns a queen clubs which he checks i bet 10 which he calls. Rivers a queen of spades which he checks i bet 20 he puts me in i call. He goes jack high flush. I go man thats an unlucky turn for me. He responds with yea its a good card for me. Everyones waiting and a guy asks him to show his hand which he refuses. He goes jack high flush you wanna muck. I go show your hand and ill muck he clocks I just grab his cards and show them. He ends up showing jack diamonds 5 spades. He tried to get me to muck so he won. Basically never felt so cheated in my life. Call the kid a scumbag and just scoop the pot. He trys to play it off like it happens in AC all the time.