They finally did it! But already split less than two years later...Ben Affleck and Jennifer Lopez said "I do" at an intimate ceremony in ... where else ... Las Vegas!

The second-time-around couple got their marriage license in Clark County and Lopez, 52, officially changed her last name to Affleck. She announced the news in her weekly newsletter that went out on Sunday, calling the weekend wedding "the best night of our lives." She called the couple's children "the best witnesses."

This was the second wedding go-around for the pair who were engaged 18 years ago but called it off the weekend before their huge wedding event was supposed to take place. The pair will blend their families -- J Lo's twins Max and Emme, 14 -- and Ben's daughters Seraphina, 13, Violet, 16, and Samuel, 10.

Sneak a peek at the lovey-dovey couple just days before the wedding ...