shame on me

Fool me once, shame on you.

Fool me twice, shame on me.

I have been ashamed of myself too many times.
My cruel and selfish sister asked me for help minutes ago.
She wasn't even polite.
She didn't even make it sound as if I'm doing her a favor.
She just made it as if I'm obliged to.
Like, "Do this or you're a bad person."
Without, polite words like, 'please, thank you'.

I just looked at the ground and quietly agreed.
Feeling guilty for not really wanting to help.
Feeling really angry with myself for being unable to refuse her.

Why can't I hurt other people the way they hurt me?
Why am I such a fool?