I’m so sorry.
As others said, this is addiction. She’s gone and the addiction has taken over and it’s as simple and heart-crushing as that.
You sound like a good guy. There will someday be someone in your lifewho won’t be a slave to addiction who will appreciate you and be a true partner. It will just take a lot of time to heal.
Advanced addicts are hurricanes. They destroy everything in their path. I know it’s impossible to see it now but her leaving you is the best thing for you.
As for all her “reasons”...they aren’t. They’re rationalizations and excuses for her to seek the shortest path to gratifying her addiction.
Getting in-person help to understanding how this has affected your own role in relationships is crucial. We come out of these distorted as to how much we should give others and how much we should expect from them and it’s too easy to fall into the same nightmare again.
Sending you a hug.