Mermaid's choice

There has been this rule that states that once a half mermaid get their mermaid powers they have to choose to either be a human or a mermaid for ever.
This happened to Katherine once.
She thought it was the hardest choice ever.
Will she ever choose or will she not.

Hi I'm Katherine and I can't decide what to choose.
If I ever become a mermaid I'll get to see my dad and to older sisters, I also get to do stuff I never did before.
But if I ever become a human I'll still be with my mom and my best friend Sierra, I also get to be with them forever.

Actually this is the hardest decision I ever made.