Sharon Osbourne 911 Tape ... A Clue to the Split?

The Sharon Osbourne 911 tape -- where she desperately calls a dispatcher asking for help after a candle at her home lit a table on fire -- may be a clue to the marital strife that led to their split.

We've re-listened to the tape -- recorded January 17 at 4:45 AM -- and you hear Ozzy at the beginning, sounding somewhat incoherent. It's possible Ozzy was no different than normal, but we now know he's only been sober for around 45 days after 1 1/2 years of abusing drugs and alcohol, so that would mean he was using at the time of the 911 call.

On the other hand ... Sharon told TMZ shortly after the incident that SHE was responsible.