Kelly Osbourne and Joan Rivers may seem like old friends on Fashion Police, but Kelly’s reportedly drunk and aggressive behavior may be threatening to tear that all apart.

The former Osbournes star, who recently split from vegan chef fiance Matthew Mosshart, seems to be in a tailspin since the split and it’s threatening to ruin her professional career.

During a recent live performance by her Fashion Police co-star Joan, Kelly allegedly got drunk and rowdy and began harassing the veteran comedienne.

“Kelly had one drink before the show started and then during the show, she got up and went to the bar to get even more drinks,” an eyewitness reports to RadarOnline.com.

While Kelly has spent plenty of time in rehab treating her substance abuse issues, it doesn’t seem as though she’s committed to a totally sober life these days.

When the time came for Joan to start telling jokes, Kelly was already out of control. “Kelly was yelling things out to Joan during the show when no one else was and she was throwing her hands up in the air. She was doing it obnoxiously. Everyone around her thought she was drunk,” says the insider.

Adds the source, “She grabbed her friend as she was leaving and was hanging onto him, it seemed so obvious that she had been drinking.”

Source: RadarOnline.com