simpsondivorce230.jpg Another one bites the dust!

Jessica Simpson's mother Tina Simpson has filed for divorce from husband Joe Simpson after 35 years of marriage. The papers were submitted Sept. 24 in McLennan County, Texas. "The marriage has become insupportable because of discord or conflict of personalities," she cited in the docs.

"Tina and Joe Simpson have filed for divorce. It is an amicable split and there is no third party involved. Any other related allegations are completely false. The family appreciates your respect for their privacy at this time," a family rep tells Us.

Days later, Joe Simpson filed a response petition that requested his estranged spouse get nothing in the split. Sounds like it's getting nasty!

Signs of trouble have been brewing for some time now. The former couple placed their shared Encino estate on the market for $4.3 million earlier this year, and Joe was arrested this past August for DUI.

Daughters Jessica and Ashlee Simpson have yet to comment.