One Cruel Joke

So, for the last two months-ish, my brother and his girlfriend have been playing one horribly cruel joke on me, and I felt I had to blog about it to "get it off my chest" per say. Around November 22nd ish, John's girlfriend, Cindy, messaged me bitching about me consoling what I believed to be my brother's broken heart. He was upset (or so I thought) and had said she was gay, and Cindy thought that I believed she was. So she decided I wouldn't be allowed to be a part of the twin's lives anymore (the twins being my nieces.) and nor could my father, and she proceeded to speak cruel words about my father. I replied and tried to be gentle in my words, in hopes that whatever I had said or done to vex her would be forgiven. It didn't happen. We fought for a few days, her with nasty words, me with gentle words and ending with God Bless you, trying to soften her heart a little. Eventually I became angry and vexed at her myself and threatened to make sure all dad's friends could see the words she had written about him, and had their chance to say cruel things about her. I never followed through with my threat because I didn't want to become like her. She then blocked me, from her profile as well as her childrens accounts, which made me heartbroken to know that I couldn't talk to my nieces whenever I chose.
I continued to talk to my brother through this, and we had our fights, and on Wednesday, he deleted me as a friend on facebook, after I confronted him about his relationship status as being "It's complicated" and he responded with he was only looking for sex. When I growled at him for deleting me, he told me to relax, that this whole thing was just a joke, and that he and Cindy were just peachy.
That hurt me deep. I couldn't, and still can't, understand why someone would do that, and how they found that process funny, when I had to suffer so badly.
Tonight I confronted my brother about the matter, but he has yet to respond. TOmorrow I will go after Cindy, as I feel I deserve and explanation for all this nonsense.