CHELSEA CLINTON‘s husband is headed to a mental hospital, friends fear, as a bitter feud between their families adds more fuel to their ongoing marriage woes.

The former first daughter, 31, is desperately trying to keep the problems out of the public eye by smiling for the cameras as she parades hubby Marc Mezvinsky, 33, around New York.

But Marc is not the same person ever since he high-tailed it back to Chelsea’s side after quitting his cushy Wall Street banking job to be a ski bum in Wyoming.

In an exclusive ENQUIRER interview two weeks ago, Marc’s first cousin Andrea Mezvinsky talked about him "undergoing a crisis" and revealed family members were deeply concerned that he was cracking up.

Sources say Marc has been deeply troubled that the Clinton clan encouraged him to break ties with his father, former Iowa congressman and convicted felon Ed Mezvinsky – and that he seems headed for a breakdown that they believe will land him in a psychiatric ward.

The sources added that Marc’s dad, now out of jail, blames Bill and Hillary for his son’s problems.

"The things that have happened to Ed since this whole Clinton situation took place are unthinkable! He’s been treated in a disgusting way by everybody involved, and he’s very upset," Margot Mezvinsky, his daughter from his first marriage and Marc’s half-sister, told The ENQUIRER.

Marc’s father lives in the upstate New York town of Wellsville. A local resident who knows him said his son’s rejection "has destroyed Ed. He has lost weight and appears disheveled."

As The ENQUIRER reported, Marc fled to Wyoming after he had a knock-down, drag-out fight with Chelsea over starting a family.

Now, with the interfamily bitterness deepening, "there’s fear Marc is headed to a mental hospital," added a source close to the young couple, who wed last July.

For ALL the details – they’re in the new ENQUIRER – still on sale!