I had the same issues as you. My mother adored my sister, worshiped her and agreed with her on everything. I was ignored. Always. Treated as an idiot.
My mother hated me, she told me that.

As I got older the pain of 'not having a mother' and of trying for 40 years to connect with her I eventuality, (and way too late) gave up.

Research on the web revealed my mother had NPD (narcissistic personality disorder) and that my family dynamic was typical.

The NPD mother (or father) picks a favorite, her prodigy, her mini me. They become psychologically fused in a abnormal way.
My sister is the same creature as my mother they move as one, think as one. Enmeshed, engulfed and unhealthy.

Both without empathy, they can be very cruel to their chosen scapegoat the one they dump all their unpleasant qualities on.
Something goes wrong in mother/sister life? Guess what? its all MY FAULT. Yup, my fault!
If they broke a nail while in Spain---------------it would be all my fault.

They connive, manipulate and lie. They are destroyers.

My advice. Give up, move on. Make a life for yourself away from these emotional vampires. Dont let them feed on you any more.

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Welcome To Light's House A Site For Adult Children of Difficult & Toxic Parents . Is your parent impossible? Irrational? Unreasonable? Controlling? Toxic?