Madonna’s fledgling marriage to Guy Ritchie is in tatters over shocking charges that he bedded an old girlfriend while Madonna was pregnant with their baby son!

The stunning revelation could spell the end of their turbulent nine-month union.

“Madonna’s furious with Guy,” revealed an insider who knows the couple. “She wants a showdown with him after her concert tour ends — she wants to know if the marriage is even worth fighting for.”

Tania Strecker, Ritchie’s leggy, blonde former girlfriend, said in an interview she was still seeing the 33-year-old director as recently as 18 months ago — when Madonna was pregnant with little Rocco, who’s now 13 months old.

“He was the love of my life,” the 27-year-old Strecker said.

Strecker’s claim is the latest — and biggest — bombshell to hit the 43-year-old Material Girl, who’s been desperately trying to paper over cracks in the troubled young marriage. Just weeks ago she was seen crying after a public spat with Ritchie and there have been reports of terrible screaming matches behind closed doors.

“Madonna’s a real control freak but Guy’s not the type to be pushed around,” the insider told The ENQUIRER.

“They’ve had lots of fights from the beginning.” In fact, the couple battled so frequently that six months before the wedding Madonna said publicly there was no chance they would marry! It was during one of these spats that Ritchie left Madonna in the U.S. and flew back to London — and into the arms of Tania and other women.

“Guy always kept in close touch with Tania — but had to keep it a secret from Madonna because he knew she’d go nuts,” said another insider.

“She’d forbidden him to see any of his old girlfriends. And Guy wasn’t just seeing Tania! He also turned up at the birthday party of another ex-girlfriend, Rebecca Green, and left with her hand in hand!”