While I do believe that you may have a problem self-regulating, I would not put the entire responsibility for how you are feeling on you.

From what you've described, your therapist has his own part in it. His way of dealing with your emails/text is not the most therapeutic and/or professional. From my experience, what helps people self-regulate is when the situation is consistent and predictable. Your therapist has been responding inconsistently. If he needed to make a change in his way of responding, he had to talk to you about it. When the therapist all of a sudden changes their response to the same behavior from the client without any explanation, it's dismissive and anxiety provoking, especially for those who have a problem self-regulating.

If you want to know my opinion, he shouldn't have engaged in the text/email correspondence to begin with. When a client sends an angry text/email for the first time, that should be a signal for a therapist that something is not working and this should be addressed and understood immediately the next session. Whatever it is that causes a client's angry reaction, it should be understood and resolved collaboratively and in a timely manner. The agreement should be reached on how to deal with the problem and, once reached, it should be followed by both parties. Any time it gets broken, there has to be a conversation about it, and, again, whatever seems to be a problem, should be addressed and resolved collaboratively and in a timely manner. This all is part of therapy work and it's the therapist's responsibility to ensure that this work gets done or, at least, to do their part to get it done since it takes two to tango.

Your therapist didn't do any of it. He didn't seem to communicate to you why he decided to respond to your text and emails in the beginning and why he changed his mind all of a sudden. He also didn't seem to be interested why you had the need to send him texts and emails between sessions instead of confronting him in session if you were angry at him. Then, suddenly, he didn't even read your last email. His way of dealing with your problem with self-regulation is dismissive and borderline neglectful and, frankly, irresponsible, which only contributes to your difficulty to self-regulate instead of helping you, which, in turn, makes you want to contact him again and again even more.. and the vicious cycle continues..

So, I wouldn't take the whole burden of responsibility upon myself if I were you. Your therapist has a good portion of his own share to carry.