I played with a guy's feelings in order to inflate my self esteem
What compelled you to use someone like that?
It felt good and made me happy.
It's good to want to feel good about yourself, but leading someone on when you don't care about them is cruel. Think how humiliated you'd feel if the roles were reversed.
If he was so stupid that he fell for that then he deserves to be toyed with.
That's really hurtful, no one deserves to be manipulated, even yourself. I believe it's best to apologize about what you did wrong and reveal your true intention. It may hurt but it's for the best and I'm sure you can find better ways to raise self esteem.