EMINEM and his ex-wife, KIM MATHERS, have said some pretty nasty things about each other over the years. But Kim may have just crossed the line.

–In a recent radio interview . . . (–on Detroit’s WKQI) . . . Kim revealed that Eminem is NOT packing.

–She said, quote, “He’s not very well endowed. If you’re going to have sex with him, make sure you have a little blue pill, because otherwise it does not work.”

–She also had some non-penile complaints . . . quote, “I can’t stand him. He’s an absolutely horrible person and he gets worse every day.

–“I vomit in my mouth whenever I’m around him or I hear his name. There’s nothing left in me for him. Nothing at all.”