Family Drama

I am estranged from my oldest sister since June 2018. Background as it is relevant to the situation today: She left Philadelphia area (where everyone in the family is) to move to Naples Florida (where I am with my husband) in 2018 after her son died of a massive heart attack at 36 yo in 2016. She had another child, a daughter with whom she was estranged because of her drug usage (which all of totally supported her in that decision). Well, right before she left to come to FL, my niece was found dead of a heroin/Fentanyl overdose. She refused to claim the body. This causes great distress in my family, particularly for me, as she was only 2 yrs younger than I , and I was appalled at this behavior. After many phone calls by me to Philadelphia I arranged for her ashes to be claimed by my brother and brought home. Shortly after she arrived, she asked me to tell her the truth about why I wasn’t hanging out with her more, etc. So, I spoke my truth in a what I thought was a judgmental way. I said that I was having a problem with Melissa and the way she was left but t hat I’d work through it and get over it. She railed on me, accused me of blaming her for the death (which I did not) and stopped contacting me. I contacted her via text on 3 other occasions since then (birthdays, anniversary of my nephew’s death, to invite her to the grand opening of my new office). She ignored my birthday and hasn’t contacted me other than to say “thank you” if I text her. I have asked my other siblings not to pressure me about going to see her because I feel that I am in a good place with all of this.
Today my brother texted me that she is alone on Thanksgiving and told me that my dead mother will be mad at me if I don’t do something about it. Needless to say I went off like a nut because he ignored my request not to do this and then he accused me of drama.

C William texted me that Mommy will be pissed if I leave our sister alone on Thanksgiving
T He has no right to tell me what to do
F Pissed
A Argue with him, tell him he’s causing the drama, tell him I don’t care if Mommy would be mad,, tell him Daddy wouldn’t be mad, justify my reasons for not inviting her, tell him to stop bothering me about this
R I an telling William what to do

C William texted me that Mommy will be pissed if I leave our sister alone on Thanksgiving
T He is just being himself and doing what he always does
F Neutral
A Thank him for his opinion, continue to do what I want, don’t justify myself, wish him a good day
R I be myself and stand firm in my convictions

This issue is a real trigger for me because I haven’t enforced my boundary that if they continue to tell me what I should do about this then I will stop talkng to then. I see this is why I got so mad. I an mad at myself more.