Dennis Quaid's Wife Files for Divorce

Dennis Quaid's wife has filed for divorce from the actor ... TMZ has learned.

According to the divorce petition filed by Kimberly Buffington-Quaid and obtained by TMZ, "The marriage has become insupportable because of discord or conflict of personalities ... that destroys the legitimate ends of the marriage relationship and prevents any reasonable expectation of reconciliation."

Kimberly is asking for spousal support and attorney's fees.

There is a temporary custody order in place, which provides that both Dennis and Kimberly each get time with their kids. The order only covers last weekend, but presumably they will get an updated order soon. The kids cannot be taken out of state or removed from school without an agreement by both parties or an order by the judge.

The temporary order also gives Kimberly possession of their main residence and the Mercedes. He gets the Cadillac Escalade and a condo.

And get this. The temporary order says, "The parties shall cooperate with one another in using the Range Rover..."

Kimberly is asking that all of their community assets be fairly divided. In Dennis' answer to Kimberly's petition, he says he wants her to get nothing.

Both Kimberly and Dennis are ordered not to say anything "vulgar, profane, obscene or indecent" to each other.

Dennis married Kimberly Buffington-Quaid in 2004 -- and together, they've been through a lot. In 2007, TMZ broke the story that their twins almost died shortly after birth because the medical staff at Cedars-Sinai Medical Center in L.A. gave them a massive overdose of the drug Heparin.

The twins are now 4 years old.

It's Dennis' third marriage. He divorced Meg Ryan in 2001 ... and actress P.J. Soles in 1983.

9:48 AM PST -- Kimberly's rep has released a statement ... saying, "We can confirm that Kimberly Quaid has filed for divorce."

The statement continues, "Contrary to what has been reported, a satisfactory settlement is being worked out for both parties. We will not be providing any further information on this private matter."

Dennis and Kimberly narrowly avoided a legal disaster in 2009 ... when they left a restaurant, seemingly drunk, and Dennis got behind the wheel of his car. Fortunately, a cop advised Dennis to get out of the vehicle before he pulled away ... and the couple got a cab home instead.