How to kill a zombie

If I were to choose an art form, it would be a song,
wordless and long so I could fill the music in
with thoughts of you all day and all night
because you do that to me, my sweet demise.
I'm happy when I'm with you,
but I hide from the sun and lurk in the darkness
when you're away because this fear is eating me like
worms eating rotten flesh.
I know one day you'll leave, as soon as you see
the monster that lives in me and it will not go away.
but I love you and soon my heart will break.
I can already hear the shattering sound
everytime it beats.