I'm going to disagree with the ladies here for once...
Rule #1) You don't destroy another person's property.
Rule #2) Why would he destroy the pictures?
There are a few things that men don't do. They don't change wallets unless they have to, they never really clean out their wallet until they change wallets, and a lot of them don't throw away things like birthday cards. You can accuse him of being jealous, or having a double standard, but you haven't actually proved that he would insist you destroy pictures of old boyfriends etc. Now, unless he doesn't like the girl, as in actively doesn't like her, why would he ever destroy anything she gave him? It makes no sense to destroy something from someone if you don't dislike them.
For all you know the card was out because he ran across it while looking for something else, and he decided to re-read it and just left it sitting there.
Instead you were confrontational, demanded that he destroy it, and then destroyed it yourself. I'd kick your ass to the curb too if I were in his shoes.
"Well, then," the Cat went on, "you see a dog growls when it's angry, and wags its tail when it's pleased. Now I growl when I'm pleased, and wag my tail when I'm angry. Therefore I'm mad."