In sickness and in health — and in prison for decades to come.

The wife of Long Island drugstore massacre suspect David Laffer will plead guilty with her husband today in the robbery-slaying of four.

Melinda Brady, 30, is expected to plead guilty to robbery in the savage Father’s Day murders in Medford, sources close to the case told The Post.

Brady allegedly drove the getaway car after the unprovoked killings of pharmacist Raymond Ferguson, 45, drugstore employee Jennifer Mejia, 17, and two customers, Jaime Taccetta, 33, and Bryon Sheffield, 71.

Brady’s husband allegedly swiped more than 2,000 pills, mostly the painkiller hydrocodone, to satisfy her addiction.

She faces up to 25 years.

Laffer, 33, faces life without parole for the four murders, to which he’s expected to plead guilty.

Before today’s court session in Riverhead, Suffolk DA Thomas Spota is expected to explain the pleas to the four grieving families.

Daniel Taccetta, the brother of Jaime Taccetta, said the relatives won’t back a deal that lets Laffer plead guilty to anything less than murder.

“He’s not going to get any break,” Taccetta said.