Major Gift by Tiffany Ezuma

From 831 Stories: 

The widow of a tech mogul is determined to give her wealth away--and keep one secret from the journalist tasked with telling her story. A hot new take on the billionaire romance.

When Ndidi Davis's husband unexpectedly dies, she's left bereft--and with $2.1 billion in the bank. She channels her grief into launching a charitable foundation, but the endeavor is made more complicated by Geoffrey Campbell, an ambitious, perceptive journalist assigned to profile her philanthropic pursuit. Geoffrey's reporting slowly uncovers Ndidi's whole heart--and some parts of her past she's worked hard to keep out of the public eye.