I am so sorry your mother treated you that way, so very sad.
And I don’t understand it but I have watched for years the way my hubby’s ex has treated their 2 boys, much like you and your sister.
The son who is treated so poorly bends over backwards to get his mother’s love, she still withholds it.
I know , there’s no explanation.
That’s sad. I have 2 boys and 2 girls. They have always accused me of have a favorite, my second son. Not true. I love them all the same.