OMG, I'm so sorry she's "taken hold" of you again - I just finished writing a long note (that would make sense to others) but I'm going to ditch it and instead boldly say,
Step back and put the responsibility where it belongs,
because YOU KNOW BETTER-
SHE is the problem, not you!

---And how do I know U know better?
Because U had such great insight and gave me such good advice when I was telling you about how awful my Mom made me feel (someone I distanced for decades for survival, but who now AGAIN + STILL made me feel I was not worthy of living).

Please read the pms U sent me 01/01 and prior, and remind yourself that people like "our Mom's" do not deserve to have any NEGATIVE power over our feelings + emotions.
As mentioned here they are narcissistic people (self-centered, manipulative, and demanding), who often blame others for their own misery (unhappiness or failures in their own lives).

YOU DO NOT DESERVE THIS! - Let her find another punching bag.

SHE is not a healthy influence in your life -
And I'm giving you the exact same advice I know you would give me.

-Sure at 15, she has a lot more control over your life/feelings than my Mom does for me at 54, but I know you r wise enough to recognize it
(the abuse + control).
UR level-headed and wise, and I'm hoping you'll soon realize that
distance from her is necessary for your own survival.

Being out of the house for school and/or other activities might be a good way to start breaking free of her control.
I don't now why ur homeschooling, but if at all possible, I think going to school outside the home (public or private), could be the first step, to distance yourself from her.
Please try,
You have way too much to offer, to let some screwed-up + miserable woman, knock you down.
And although I hope her nice gestures are a sign that she realizes she's gone too far, you can't risk letting her have such a big influence on how you feel about life.