I do not understand why DNA or family relations should mean you have to keep such a toxic person in your life. Sure, make an honest effort but if it's not returned... accept it. The truth of the matter is not everyone loves or even likes everyone, and that's okay. It's still the truth even if the other person is family. And if the other person has done some very repugnant things - wish death to you, threaten you, harmed you - then it makes no sense to stay in a relationship with them.
There are always 2 sides, no, 3 sides to a story. I understand that. But when the "other side" has made it quite clear they want nothing but ill will for you, I'd take a hint & remove them from my life.