Congratulations for you for choosing the healthier response to your emotionally unavailable and abusive mother.
As I was reading your post I noticed how your mother used the information of her changing her phone number as the "hook" for her real motivation for calling you. Namely, that she wanted to tell you of her conversations with her sister, etc.
As long as you were the passive listener to what she had to say, she was fine.
The moment you asked her if she was hearing you - really hearing you and the pain you were expressing, she hung up.
The interaction was no longer about her. As a result, she didn't have an interest in continuing the contact.
It hurts to have someone so self absorbed that they are not willing to hear the pain of another, let alone offer to soothe it. That pain is compounded when the disinterested party is a parent.
You asked whether or not you are "responsible" or "to blame" for the "failure" of your relationship with your mother.
The answer is a resounding NO!
You said it yourself "she NEVER made me feel emotionally safe. EVER." The difficulties in your relationship with your mother has everything to do with her narcissism. You were not responsible as a child and you are not responsible as an adult, for taking care of your mothers feelings.
But as the adult who is gaining insight and the inner strength to utilize that insight, you are responsible for how you choose to interact with your mother.
You chose not to be manipulated by your mother, both by what she was telling you, and again by her emotional reaction.
I am sorry you are hurting.
I applaud that you chose not react to your mother and that you chose to empower yourself to meet your needs.
Kudos to you.