That is wonderful! You have so much to be proud of. And 3 months later, I imagine you're even stronger. Way to go!
I can relate to much of what you say. My social anxiety tends to be work related, with social anxiety, perfectionism, and fear of interacting with certain authority figures all intertwined and feeding each other. I'm in week 16 now and have been seeing improvement in this area since I started the series.
Something else I've been learning is how I often blame myself, feel guilty, and especially internalize my mistakes. Like, "I'll be judged if I mess up" as if it's a personal attack against my ego. When really, everyone makes mistakes, even when they try their best, and managers are thinking about reaching solutions and bettering the system as a result of mistakes.
When a mistake should be addressed with someone else, owning up to it along with suggesting a solution and improvement can show that you care about your work enough to resolve the issue and are thinking of ways to make the system/process better for everyone.
I think it's great that in addition to the emails back and forth, you took the initiative to let your boss know you wanted to talk more about making the correction, to make sure you understood what was needed. Great job!