Thanks for the honesty. Now go on to prison for 15 years.

Manhattan prosecutors are playing hardball with a rapper who walked into a Harlem station house last year and copped to a 17-year-old cold-case shooting — only to learn that the victim had died and that he’d just confessed to murder.

Prosecutors want Diddy protégé G. Dep, a k a Trevell Coleman, to get 15 years, the minimum allowed on a murder plea.

Coleman has said that he spoke up as part of a 12-step drug-rehab program — and “to get right with God.”