Dak Prescott, Sarah Jane Ramos Alert Wedding Guests Of Cancellation

Dak Prescott and Sarah Jane Ramos have informed their wedding guests the ceremony is officially off ... and TMZ Sports has obtained the email the former couple sent out to apologize for the last-minute cancellation.

We received the note from one of the 250 people slated to attend the destination wedding in Lake Como, Italy on April 10 ... which reads as follows:

"It is with heavy hearts that we privately inform our attendees that we have made the very difficult decision to cancel our wedding. We deeply apologize for any inconvenience this may cause you and we welcome your prayers."

The email was signed, "Sarah Jane Ramos and Dak Prescott."

We broke the story -- the couple had been dealing with issues for months ... but we were told Sarah Jane ended things for good after a massive argument during their joint bachelor and bachelorette parties in the Bahamas.

There is a ton of speculation surrounding the split ... but our sources tell us the rift had nothing to do with a prenup.

As we previously reported, the two sides are solely focused on coparenting their two young kids now ... and there's no chance of getting back together.