AITA for demanding thousands of dollars from my mother to get back into my life?

When I was born, my dad's rich grandparents had started a savings for me so that I could be ready when I turned 18. Every birthday, they'd put 1000 dollars into the savings.

My mother has always been an addict. Hard drugs, cigarettes, etc. I was around 5 when my dad decided enough was enough, and he wasn't giving her any more money. So, she started stealing from me instead.

Every month she'd take a few bucks for cigarettes, or a hundred to pay off shady debts. Those little chunks added up.

When turned 18, and I found out that she was stealing from me, I confronted her about it and she admitted to it, bragged about it. "I didn't have a good start, why should you?" When she said that, I disowned her as my mother.

She's now coming back to me at 20 and begging for my forgiveness, and saying she wants to be my mother again. Yada Yada. I told her that her apology meant nothing, and I wanted to see her make up for it in full. She'd have to pay back the upwards of 10,000 that she stole, and only then would I allow her back into my life.

My family is now calling me an AH for "extorting", "blackmailing", "abusing" my mother. My brother is avoiding me, my cousins are all calling me a petty train wreck, and I'm getting flamed on Facebook.

I have nothing left to turn to, so here ya go, Reddit. Pick me apart like the internet does. AITA?