The 57-year-old man, who cannot be named, stored his sperm at a respected IVF clinic in Cambridgeshire, after he was told a drug treatment for arthritis might make him infertile.
But two months after he and his wife separated she forged his signature and persuaded doctors at the IVF clinic to fertilise one of her eggs.
She gave birth to a daughter and a son after visiting the clinic twice - but did not inform their father on either occasion.
The man, who by this time had a child and pregnant second wife, only found out about his kids when his ex-wife's sister phoned to tell him his son was critically ill in hospital.
The man told the Daily Mail: 'I was stunned when I found out she had withdrawn my sperm without my consent because at the time we had split up and were going through a divorce.
'It was a deliberate act to bring two children into this world without a father to look after them. I was never at the clinic and I never signed the documents.'
The stress of it all has turned my life upside down.'
He has now called for a change in the law to ensure no other parents go through his torment.
The man stored sperm in 1999 to ensure that he and his wife of 20 years could have a child if drug treatment for crippling arthritis left him infertile.
However, in June 2000 the couple decided to divorce. Just weeks later she visited the IVF clinic and forged his signature, allowing doctors to create embryos from his frozen sperm and her egg.
She gave birth to their daughter in June 2001 before returning to the clinic and giving birth to their son in September 2003.
The man, who remarried in 2002, was forced to tell his new wife, with whom he has two daughters aged eight and seven, and his family about his other children.
He explained: 'My new wife has been amazing about it all. She speaks to my ex-wife to do the best for the children but it has put a strain on our relationship.
'First of all I saw the children in a contact centre but now they are allowed to come to my home every other weekend and they get on very well with my other children.
'This has affected many lives, including the four children, and it is something that will be a strange situation for us for the rest of my life.
'The older girl had been into my house to visit my dad who was dying and I didn't even know she was mine. My dad died not knowing he had a granddaughter.
'When the girl got older my ex-wife texted me saying she wanted to see her father. The children asked their mum where they came from and she told them 'the freezer'.'
In 2007 the man's ex-wife demanded he pay an extra £100,000 after she fell into debt caring for their children.
The judge ruled the first divorce hearing was unfair because it did not take the two children into account and the man was forced to pay the money for the children he had unknowingly fathered.
He now sees his IVF children, aged nine and seven, for two days every fortnight but hopes they will remain part of his life.
The woman, 51, who forged her ex-husband's signature so she could have his children by IVF has refused to apologise and revealed she would 'do it again.'
She said: 'I don't believe I have done anything wrong. It was getting later and later for me and I wanted to have a child. If I had not done it then I would not be blessed with my children.
'I have no regrets - I would do it again.
'The children known they came from the freezer and the younger one says he comes from Iceland, but they know they are loved.'
More IVF mix-ups here.
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