Tania Joya fled to Syria after being radicalised by jihadi husband John Georgelas, who is now dead.
But she fled ISIS six years ago and now works with organisations to counter extremism.
Now she has turned her attention to Shamima, who has asked to return to the UK after fleeing east London for the death cult in 2015.
Tania told Grazia: “She’s still a child in that she’s not thinking like an adult and she needs psychiatric help. She needs education.
“She needs to be brought back to reality because she’s so brainwashed.”
Shamima had sparked uproar after saying she felt the Manchester terror attack in 2017 was “justified” because of airstrikes that have killed civilians in Syria.
“I think that’s trauma. PTSD. I believe that’s a coping mechanism”
Asked about her lack of remorse for the atrocity that killed 22, including children, Shamima said: “I think that’s trauma. PTSD. I believe that’s a coping mechanism.
“She’s been through starvation and seen two kids die and she wants to blame the people who attacked her home, even though she broke the law by going there.”
Shamima – married to Dutch jihadi Yago Riedijk – has recently given birth and claims she needs a return for the sake of her baby.
But the Home Office told her family it plans to strip her of her citizenship.
It is understood they made the move because it is through she has dual British-Bangladeshi citizenship, which would not leave her stateless.
However, Bangladesh has denied this and say there is “no question” of her entering the country.
Shamima’s dad, Ahmed Ali, has called for his daughter to face justice in Britain.
He told ITV News: “I don’t think he’s (Sajid Javid) done the right thing because she is a British citizen, and if it turns out she has committed any crimes, then she should face justice in the UK.
“She belongs to this country, she belongs to England.
“My daughter was a little child, she made a mistake, she didn’t properly understand.”
The Home Office has declined to comment.