This sounds like a really difficult situation. The sarcasm ("Nice. Real nice.") and the door-slamming are gigantic red flags to me. Even if your T was having the worst day ever, her job is to put her personal issues aside and be present with you without getting angry or impatient. She needs to be strong enough to weather the storms while you work through the intense emotions that you're learning how to handle.

I haven't seen the article you reference about challenging people with avoidant attachment styles, but I'm wondering whether this T is capable of doing it. It seems to me that the way to challenge avoidant attachment is to show you that intense connection with another person can be safe and predictable. Her behavior isn't either of those things. You need stability to feel like you can safely show somebody all the confusing and stressful things you are dealing with right now. Nobody has the right to belittle you, especially not a therapist.

It also worries me that your T was dismayed when you wanted to revisit something that is clearly a pressing concern for you (the ""Oh God, not again" thing). It's your therapy, and she should trust that you will talk about the things that are important for you to talk about. Even if it's the same topic every week for six months. She should help you process things in different ways, look at them from different angles, and GENTLY try to help you out of the loop if she feels (after listening attentively for a very long time) that you are stuck.

My opinion is to maybe look for a new T who specifically mentions having training and experience with LGBTQ issues. Maybe even look for a queer-identified therapist. I had one when I was coming out, and it helped enormously. I felt safer and more understood before I ever told her anything because I knew she would understand what I was going through, based on her personal and professional experience. Secondly (but not less importantly!), make sure this new T has the ability to hold the boundaries that make your therapy all about you, because it absolutely should be. You want somebody who will listen to everything you say and who will respond to your intense emotions with empathy and curiosity, not frustration. It sounds like things really have gone awry with your current T, and that is truly unfortunate.