Yankee pitcher CC Sabathia took to the bottle because of mounting physical and mental issues, a family member told The Post Tuesday.

“It’s just a buildup of what a person is going through: stress, physical things, life in general,” said his aunt, Gloria Rufus, who lives in Vallejo, Calif.

“It’s just a combination of things, and it was time [to go to rehab].”

“I think he’ll be OK,” she said. “I know it takes a special kind of person to say, ‘I need help.’ ”

On Monday, the former Cy Young Award winner announced he’d be skipping the Yankees’ postseason to dry out in a rehab facility.

The last straw was a weekend bender in Baltimore during the team’s final regular-season series, sources told The Post.

Sabathia, 35, spent the entire weekend boozed up — and appeared “out of it” in the clubhouse last Friday, the sources said.