My wedding is next week and I’m miserable

I’m getting married next Saturday, but my mother and brother are making me miserable.
Long story:
My brother is a waste and very manipulative. Everything wrong with my bro my mom says about my fiancée (my bro doesn’t work, abuses drugs). My brother even went and contacted my friend/coworker about how awful I am. He easily called me the c word about 5x. When I said something to my mom about it she said "well you and her shouldn't have been talking badly about us". This past weekend my mom wouldn't stop saying how awful I am, how ashamed she is of me, how I'm a heartless bi@!h and I owe her an apology. Yesterday I was having a session with my therapist in my car and my brother starts texting me all this nasty stuff. He then said he hopes my fiancée commits suicide like his father. My mom threatened to go to the priest and tell him how awful I am. Now my brother is contacting family members. I’m so embarrassed and miserable.
Thanks for letting me vent. I’m sorry this was such a long post