Just for Her by Suzanne Jenkins

Single mom, Annie Marley has her hands full with a toddler, a full-time class load getting her Master’s degree, and a job at Maggie Angel’s animal rescue.
With the blessings of his adoptive parents, Chris Harcourt submits his DNA to a genealogy site. He quickly finds his half-brothers, the Chastain boys, giving new meaning to the battle cry of the single women of Cypress Cove, “Don’t you have a long-lost brother?”
Their romance is on shaky ground when during one weekend, Chris’s ex shows up, his two sons ask if they can live with Chris and Annie, followed by problems that no one expected. How strong is their bond?