You are on an emotional roller coaster ride from hell, and any contact with her is designed (instinctually) to keep you in emotional turmoil. Essentially being held hostage.
I’m going to share with you what has helped me, and try to outline this as best as I can.
To go no contact, all avenues of communication need to be shut down. No access to your phone, email (block; block; change numbers or email address if you must). Do not answer the door, talk to mutual people, trigger yourself by looking at old communication or social media- nothing.
Ways (from level of severity) for a person to get through are:
-seeing the person face to face; seeing them in line of sight (out some where); talking to a mutual person; talking on the phone; texting or emailing/ letters; in thought (somehow getting a photo to you or something, in hopes of sucking you back in).
The entanglement is probably such at this level that breaking contact is most likely triggering you from your end (abandonment issues, anxiety, your own empathetic qualities sucking you back in and laying you down on the tracks in front of the moving train), so you focus 100% on getting yourself stable and supported. Friends, anyone you have in your life to talk to, support groups, forums, therapy, books, helpful youtubers, etc.
Anyways, you are probably more ready to get off the roller coaster ride than it seems (when in the middle of an emotionally charged situation, you might not necessarily feel ready). But you can do it! Good luck.