Your brother sounds both unbalanced and dangerous. I would do everything you can to protect yourself. Ask for your parents to come with you to your therapist to help deal with his abuse. Anyone who tried to kill you, beat you to death, broke your pet’s leg, threatens you, and doesn’t know how to have respect for you needs to be dealt with more directly. Explain the idea to your therapist. A family meeting about the history of his abuse, and the upcoming wedding and what to do about it needs a professional. Simply ignoring him isn’t the answer.