How do you deal with toxic family members?

Hi I’m just wondering if you ever experienced a family member that was toxic and how you dealt with it.

I moved away from my country around 3 years ago now, but my only sister is bringing me down all the time, she has always been toxic but is becoming more and more, for example it’s been an year that I haven’t visited the family due to personal circumstances and she asked me to take the plane during a world pandemic obviously I don’t want to risk it so she was like You don’t give a damn about us and your nice along with other things.

As she is my only sister and my mom is implying that she would end her life if her only two daughters don’t speak so I feel stuck.

I feel like even though it’s impacting my mental health it’s hard to let go, especially that they’re all I have, don’t have any other family member.

Please give a girl some advice!

Edit: I forgot to mention that she is a 27 years old adult