You could probably care less about Matthew McConaugheys mother and even less how she killed her husband with her ferocious vag... but is sure does explain a lot about Matty.

In her new book, I Amaze Myself! (iamazemyself.com), Kay McConaughey dishes on everything from her son Matthew's conception to how her husband died in a compromising position with her!

"On Monday mornings, he and I often said goodbye by making love," Kay says exclusively in the latest issue of Us Weekly. "But one day, all of a sudden, it just happened. "I knew that something was wrong, because I didn't hear anything from him. Just nothing," she says. "But it was just the best way to go!"

And when her man couldn't be revived, she made sure he was taken from the house in the buff. "I was just so proud to show off my big old Jim McConaughey -- and his gift," she says.