The Daily Express quoted Banderas as telling U.S. talkshow host Ellen DeGeneres: "Let me explain to you. It was actually in some magazine that I said that I gave an ultimatum to my wife. That I present the matter of divorce (sic) because she has been involved in addictions and blah, blah, blah...
"Melanie has been addicted for many years and we always came out. We said it out loud. It was OK, we were never embarrassed of the situation but... she was clean and sober for six years."
The Shrek actor added that Griffith feared her relapse into harder drugs was imminent after she started on prescription drugs following a skiing accident at the start of 2008.
Banderas said: "In March, she came to me and said, 'I'm feeling a little bit weak in my determination for this (to stay sober)... so I just thought to go to rehabilitation by myself.'"
The 52-year-old Griffith has struggled with booze and drugs in the 1970s and 80s, and has had a stint with the rehab unit twice.