Britney Spears’ spur-of-the moment wedding resulted from a secret dating relationship she kept under wraps by quietly seeing her beau when she went back home.

While reports have called the Las Vegas wedding a booze-filled “joke that went too far,” The ENQUIRER has learned that Britney and her groom Jason Alexander were sober while tying the knot — and Britney even cried tears of joy during the ceremony.

The issue that goes on sale Friday details the couple’s wild weekend in Vegas, reveals Jason’s violent past … and much more.