You call that as a little insecure.
I call it as a little stupidity.
I believe she fell for you for some other reasons at the first place.
Not just because you could write a poem.
Your ability to write a poem is a bonus, I think so?
If you're insecure and afraid that she might getting back with her ex just because her ex could sketch, I think you better taking care some other stuff rather than worrying this stupid insecurities.