The Harry Potter star made the revelation during an interview on BBC Radio on Friday (16May14), explaining how thugs had set fire to an oily rag and posted it through the letterbox of the home where she and Henry lived.
She said, "It was massively shocking to me. Someone put an oily rag through our front door and tried to burn us down. Luckily I woke up and smelt it, otherwise I'm not sure we would be here."
French also insisted the U.K. is still struggling with racist attitudes, adding that Henry and their mixed-raced daughter Billie are the victims of "snidey" remarks.
She added, "It's the little snidey comments or things people think it is Ok to say, a kind of gradual erosion that I find particularly dangerous."
French and Henry divorced in 2010 after 25 years.