Jo Smith has revealed she has been left "scarred for life" after discovering the body of her cyberbullied sister two weeks ago.
In a heartbreaking interview, the 16-year-old today told ITV's Daybreak that she was struggling to cope with living in her family home after making the horrifying discovery.
Hannah is said to have endured months of torment on controversial question-and-answer website Ask.fm, including abuse from some users who urged her drink bleach or to kill herself.
The 14-year-old from Lutterworth, Leicestershire, was founded hanged in her bedroom two weeks ago.
Her sister Jo, today revealed that her whole family has been left in a state of shock following the teen's death.
"It's just really scarred me for life. I cannot go upstairs any more because I just imagine how I saw her last," she said.
"I just can't last in this house any more."
Hannah's older sister said she herself had stopped using Ask.fm - which allows users to ask anonymous questions - after being called "horrible things" just months before her sister's death.
"I used it about four months ago and got called a slag and horrible things, so I stopped using it," she said.
"I didn't really get very nice questions - there were no nice questions."
She added that Hannah had also kept her use of the site a secret from her big sister, setting up another Facebook account which she used as another way of accessing Ask.fm.
"She used a different Facebook (account) to what we could see - we couldn't see that one so we never knew," said Jo.
She added that she thought teenagers needed to be taught how to deal properly with abuse received online, as her father David called for "new regulations" to govern social media sites to "stop these trolls doing what they are doing."
The comments came as Ask.fm today introduced a range of changes in an effort to make the site safer.
Co-founders Ilja and Mark Terebin said an audit into the site and its safety features has now been completed, with changes set to include a more prominent "report button" on the site, and more staff hired to work as moderators.
It will also create an extra website for parents, as well as incentives to encourage people to register to use the site.
In a statement today, the site's founders said they were keen for young users of the site to be "in a safe environment."
"At Ask.fm we want our users to be able to have fun, share information, make friends and express themselves freely," they said.
"In the light of recent events highlighting the impact online bullying and harassment can have on young people, we engaged professional advisers to conduct a full and independent audit of our site and its safety features."