The Grindhouse star insisted "lifestyle differences" were the cause of the break-up, but she now reveals it had more to do with her ex's cocaine use.

She tells U.S. talk show Watch What Happens Live, "It's one thing to party every now and then, but when it becomes a full time (thing)..."

When host Andy Cohen asked her to expand about what caused the breakdown of the romance, MCGowan simply said, "Scarface," adding, "Think about it Andy... What was Scarface about?"

The classic Al Pacino film chronicles a Cuban-American's descent into drug abuse.

MCGowan is now married to artist Davey Detail, while Manson has enjoyed a string of high-profile romances with the likes of Dita Von Teese and Evan Rachel Wood.