>>At that I felt, and still feel, so used.

Nuff said. It doesn't matter if he's your cousin or anything, when he makes you feel this way, you should stay away from him.
Don't let him hurt you.
You told him about your feelings and he just didn't care (and still doesn't). This guy does not deserve the attention you pay him.
Try to meet other guys, just to get some new input. Don't focus on him, he's not as great as your imagination tells you.