How Do I Get My Former Family to Understand I Want NOTHING to Do With Them?

It's kind of a long story. My Swede father took me to Sweden on "vacation" when I was 2 and did not return to Florida. He was young(only 19) and did not want me to be raised by my mother for some reason or other and gave me to his own mother instead. My mother filed one appeal and was denied so I grew up in Sweden. My father was always honest with me and told me I have a mother on Florida who does not want to come visit me. Last year I decided to seek her out since I am now 19 and attend university. What I found was VERY BITTER&SELF-RIGHTEOUS woman. She lost the legal appeal due to being "economically&ethnically disadvantaged" but she kept tossing out the word "stole" to me as in "While you're saying you love being in ******* Sweden so much just know that ************ stole you! You are just like him! He always thought you were better than my other children! Come see you? Why the Hell would I do that when he stole you? Evidently I was not needed and nobody cared what I thought! Don't come knocking on my ******* door now that your grown! I have no use for you!"
When I approached my father for answers he said that her attitude was the exact reason he took me to his mother in Sweden. He did not think I would be treated properly by her since I am 4th of her children and she resented the interest my father took in me. As he put it "She did not treasure you. I saw you were not thriving properly. You are better off without her."
I accepted his answer and do not resent him in the least for bringing me to Sweden. My life here has very good.
Recently I was contacted on social media by a woman claiming to be my sister. I politely responded that she could not possibly be my sister because I live in Sweden and did not have any African relatives. In a very verbally reply the woman said she was "Black not ******* African" and she was my sister because we have the same mother even though I was a "snobby bitch". Again I approached my father for answers. He confirmed that though he had never felt it was important to mention my mother is a Black woman. She has two daughters and a son.
I had enough unkindness and verbal abuse to last a lifetime. I told this woman to NEVER contact me again and I want NOTHING to do with anyone in her family and I no longer consider her mother as my mother. I left Florida in 1996 and do not see myself EVER looking back. Despite me stating my disinterest my former mother's children continue to harass me on social media. I regret ever reaching out. Now I cannot get rid of them!