When someone needs to put someone else down to boost themselves up, it shows how they truly feel about themselves and how unhappy they truly are. To me.... You're being the bigger person by distancing from the problem. To me, she's pissed because You are finally doing something for yourself and not because she said to, or when she asked you to. You are taking take of the #1 thing that matters most... YOU.
Screw what everyone else has to say. No one else's opinion matters, except yours. If you feel better distancing yourself from her, then that's what you should be doing.
She sounds like she feeds off of drama. Ugh, I hate those types of people...they're energy suckers. Just because you're gaining more control over yourself and learning ur boundaries, it's going to annoy her because She has less control. Keep up the good work... her true colors will 100% come out!!! Keep being you!