Now ex boyfriend rejected birthday gift before we broke up

My now ex boyfriend rejected a birthday gift I gave him. They were concert tickets to a show he really wants to go to. I spent a lot of money on those tickets. I gave them to him before we broke up. When I first gave them to him, he said he loved them and thanked me. An hour later, we broke up and asked me to get a refund on the tickets, which I can’t do. The breakup had nothing to do with the tickets, by the way. Then I find that on Instagram he told his friends last week that he just bought his ticket to the same concert at the same place. I feel really hurt. Why would he do that? I feel it was a slap in the face and the biggest F YOU. We had some issues where he really hurt me, and I him, and it may be possible he feel guilty if he had accepted the gift. But those tickets were for him. Now I am out that money and I don’t want to go to the concert by myself and none of my friends like that kind of music. I feel hurt because he rejected my gift, then went and got himself the same thing. How should I feel about this?