The 50-year-old told producers of the new ITV documentary that "life's fallen apart".
Merson is no stranger to excess having previously lost £7million on alcohol, drugs and betting problems in the 1990s.
But some of those issues have sadly returned.
He said: "I'm struggling with life at the moment, struggling badly.
"Life's fallen apart – gambling…I've just completely lost control, I've completely, again. I'm digging a hole – I can't get out of it. It's the worst addiction in the world."