I think he was brave to bring the fraud case. It is clear that she got a more generous settlement because they had three children and that she knew these children were not his. Money never changes the hurt from the past, whether it is in a negligence claim, a fraud claim or anything else. It does set a legal example though and provide some sense of validity to the wronged party's sense of grievance.
With regards to his settlement, the school fees were paid in a lump sum at the time of divorce. After that he paid £30,000 a year after tax. To take home that much, his ex wife would have to earn £40,000 a year, which is quite a good annual salary. This would be about 50K of his higher rate post-tax income. Add in day school fees (almost certainly a minimum of £15K per child per year of post-tax income, so an equivalent of a gross income of 65K/year, this means that she was receiving the equivalent of £115,000 per year from him in children's maintenance and school fees alone, after also having received a very generous divorce settlement that made her rich enough never to need to work again. Had they divorced without children and with her being honest about her infidelity, she would have been given a fraction of what she received, so she did very well out of her deception.
Furthermore, her affairs meant that his infertility was never investigated and his cystic fibrosis diagnosis was delayed by more than 20 years. This means that he was denied the opportunity of receiving treatment that would have help preserve his health and slow the progress of the disease. He was also denied the opportunity to have his own genetic offspring if he wanted to.
None of the above changes the fact that he clearly loves his boys and is their legal parent. However, that emotion should not get in the way of recognising that this woman committed a crime and is jolly lucky to have got away with a £250,000 out of court settlement.