Example French conversation

I just want to practice the word 'casser' which means to break. When I was memorizing the vocabulary, I always imagine breaking a glass, but then I always forget it. So I thought of something easier and the perfect answer - A heart. Of course.

So I made this simple conversation. I don't even know it it's perfectly correct. But hey, at least I tried.

A: Tu as cassé mon cœur quand tu l'as dit

B: Serieusement?

A: Bien sûr. pourquoi tu ne crois pas?!

B: Je suis desolé.

A: Je rigole. :P

[A: You broke my heart when you said it.

B: Seriously?

A: Of course. Why don't you believe?!

B: I'm sorry.

A: Just kidding.  ;P]