Dump him, he's broke your heart and hurt your feelings.
I think you need to take one step back from the relationship. I have a pal and we never send each other cards but get the occassional call or catch up twice a year.
I never got a single card-even my Dad sneaked out to the post officee to get me one as he forgot.
I never tell pals my b'day and keep it hush so I can enjoy my day myself even GF forgot!
So I MTFU.
But if someone sent me one I would make sure I would send them one too-so I understand you're miffed.
It's your Birthday-organise a party next time? and MTFU and stop sending you pal birthday cards-they'll soon get the drift if they're not busy.