Are you sure you want to hear it?
My analysis:
I said "promise". I don't lie. Its not a joke. If it is, I'll write you another poem. If you're too scared then I completely understand.
Promises are made to be broken. That's an old saying.
Sometimes you may not be able to go through with the promise, i.e. if something else comes up. The lie and joke can go hand in hand. You've lied before by playing a joke, even though it wasn't an intentional lie but in the end, it was still a lie.
You can't write me a poem yet because you have others you have to write for first.
Lastly, I've already responded to the scared statement.
Overall, your logic is flawed.