Alan Henning, a 47-year-old taxi driver, went to Syria to help deliver aid to refugees and orphans in the war-torn country.
In December 2013, he was kidnapped by ISIS agents and held hostage for 10 months.
His family campaigned desperately to have him released, but, tragically, the terror group released a vile video of his beheading last October.
Speaking for the first time on The Jeremy Kyle Show, Lucy Henning revealed that she found out about her father’s murder when she logged onto Instagram - and spotted a horrific image of his execution.
She said: "I remember thinking we have had a few days, no news, it's looking good. We thought they might actually let him go.
"Then I remember I was just laying in bed on Instagram and er, I just saw the final picture. It was the final picture, after the execution.”
She continued: ”You just kind of go through in your head, like whenever I used to get upset about it, I used to torture myself thinking, 'You don't know what he's going through,' so how can you sit there crying.
"So I used to just shout at myself, you can't cry, you can't be upset, think about what he's going through, think about what everybody else is going through."
When asked if she ever thinks about her father’s killers, Lucy explained that she is still trying to come to terms with his death.
She added: “I try not to think about them. I think I'm still numb.
“I just try and get everyone to remember like, the kids that are still there, when people say, ‘Oh you've lost your dad.’
“Yeah I know but there's kids there that lose all their family in one day and they are stuck there on their own.”
The brave teenager, just like her selfless father, wants to visit Africa and do something to help children in need.
But she has said that she isn’t quite yet ready to visit the region in which her father was killed.
Lucy said: “There's an academy that's been set up in my dad's name, the Alan Henning Academy, for Syrian children, just on the Turkey side, and it's schooling around 400 pupils at the moment, getting them the education they need, so I would like to go and visit.”
What an amazing young woman; our thoughts, as always, go out to her and the rest of Alan’s loved ones.