Hiding the Alpha's Heir

Seraphina Beryl, Luna of the Rising Diamond pack and Marchioness of Blackmont, caught her mate, Alpha of the Rising Diamond pack and Marquis of Blackmont, sleeping with a courtesan. Not only that, she caught that Desmond has been kissed by their Beta's sister. 
She is not a fool to stay with him anymore. She decides to abscond from their pack and abandons her Luna duties and her marriage with him.
However, at that moment, she finds out that she is pregnant with his pup. After five years of being married to Desmond, she finally conceives a pup.
How is she going to hide the next heir of the Rising Diamond pack from Desmond? Can she be able to escape from Desmond's grasp once he finds and reclaims her and their pup? What will Seraphina do if that happens?