Deli-
I am thinking so much about everything you wrote....and I don't know exactly what to say.. My brain isn't working properly right now...so let me just give you some of my quick thoughts and impressions...fwiw...

I love your pdoc's analogy about him being the armor. I love that he wants to protect you.
And I have to admit, I'm kind of glad that he wants you to stay with Austin-T.
The thing about the meds scares me. Have you ever thought about getting rid of that stash? I wish you would. Having that kind of thing around can serve no good purpose.
Wow how awesome that you gave him the letter. You are very brave. And it's ok if you don't want to talk to him about it right now. That is a big step. I think your feelings about it are totally understandable, but I am here to tell you, you are NOT filfth, you are not an *****, and pdoc doesn't think any of that about you. Please believe me.
I'm glad he called you - shows he DOES think it's important. And it IS important. You are allowed to write and give it to him. That does not cross any boundaries, I promise it doesn't. He still gets to set his own boundaries, because he can choose not to read it until a certain time, or to call or not to call, etc.
I am so hopeful for you.....you are making good decisions....HARD decisions....... and you are coping, and even though it feels awful, I am just really hopeful that brighter days are ahead.

Please be kind to yourself.