High School student Brandy Vela, 18, took her own life after being relentlessly trolled by anonymous Facebook users.
She had sent her family a text message before shooting herself that read: "I love you so much, please remember that, and I'm sorry for everything."
Her family then returned home to find the teenager in her bedroom and begged her to put the gun down. But she shot herself with her parents and grandparents in the same room.
Now sister Jackie, 22, has paid tribute to the "beautiful" young woman and described her last moments.
She told Click 2 Houston : "I heard someone crying so I ran upstairs and I looked in her room and she's against the wall and she has a gun pointed at her chest and she's just crying and crying and I'm like, 'Brandy please don't, Brandy no,'
"I was in my parents' room and I just heard the shot and my dad just yelled, 'Help me, help me, help me.'"
She told how sick bullies set up fake Facebook accounts to harass her and, speaking to CNN , recounted the cruel taunts she received.
She said: "They would say really, really mean things like, 'Why are you still here?'
"They would call her fat and ugly. She was beautiful, absolutely beautiful; the only thing people could find to pick on her was her weight."
Brandy was taken to a local hospital where she was pronounced dead.
Police have said they have been unable to track down the bullies as they used untraceable apps to post their messages.