How can I make my ex boyfriend REALLY jealous?

He tried to make me jealous and he did. Because I dumped him because i dint feel the same way for him. It hurted him, but I dint want to hurt him. He tried to make me jealous over a girl ho is 12 and he is 16. They arejust playing around. They even put on facebook "he is married to her". It ripped me apart inside. He wanted to make me jealous so he did. So I want to make him jealous back so he can see how does it feel to be jealous and depressed. PLEASE NO RUDE COMMENTS