Don't let a troll push your buttons. If someone keeps taunting you on social media, block them. There's no reason to subject yourself to their nasty remarks. A misguided sense of loyalty is prompting you to keep the channels of communication open with a relative. Although your desire to maintain this relationship is admirable, it is creating undue stress. There's no reason you should keep talking with someone who treats you in a disrespectful manner. Life is too short to tolerate haters.