And they're my sisters?

Much like the cinderella book...
Theres me and them, just take a look...
The two of them they are as one...
Knock the sister back! what fun...
I watched for years, I read you both...
I stood on back, I took my oath...
To never trust a word you say...
Deciet was just your way of play...
Your bitter jealousy, yes it reined...
But strength in me, in time I gained...
To stand up strong, and tell you straight...
To be my sisters, its too late...
I loved you both, but you did not...
You'd bully me, I'd lose the plot...
You evil, skeaming, lying fools...
With that not there, you had no tools...
To use against your youngest sis...
With you out of my life now, its just bliss...