"Baseball Wives" -- a new show debuting tonight on VH1 -- is in meltdown mode, because one of the women is so out of control, she's threatening other BB wives with a 12-inch dildo.

During a recent filming, Anna Benson -- the wife of former Mets pitcher Kris Benson -- got into it with Cheri Knoblauch -- wife of former Yankee second baseman Chuck Knoblauch.  Anna got creative, pulled out a stun gun and set it on a table in front of her in a threatening manner, then produced a 12-inch dildo from her purse and started swinging ... which raises the question, Why such a big purse?

Sources connected with the show tell TMZ ... some of the staffers are now threatening to quit, because they can't handle Anna's insane behavior.

Sources tell us ... show execs are trying to contain Anna.