Omega May by Anna Wineheart

Madden had one job—to kill an alpha. Instead, he fell in love.
Trapped in a pack that murdered his parents, twenty-year-old Madden craves one thing: freedom. For three years, he’s been living on the streets, afraid the Dastrels will target him next. On a failed escape attempt, the Dastrels make him an offer: end the police officer patrolling their territory, and he can leave.
Madden has thirty days. It should’ve been easy.
Except he breaks into the officer’s house, and… it’s been a long while since Madden’s felt this safe.
Freshly forty-five, and envious of his brother’s pups, Officer Gabe is painfully aware of his failures. He couldn’t save his dad. He isn’t good enough.

The last thing Gabe expects is to find a young omega in his house. But Madden isn’t a burglar, and as Gabe probes into his… circumstances, he realizes Madden is in heat.
Madden begs Gabe to make him scream. Despite his misgivings, despite their age difference, Gabe relents. And Madden conceives. Gabe imprints on an omega he never meant to touch.
As their mistakes draw them ever closer, will Gabe and Madden learn to trust each other, or will their pasts run them to the ground?