Shawn Southwick: Cheating on Larry King with Hector Penate?

hawn Southwick alleges Larry King cheated on her with her sister.

That would make the CNN fossil a dirty, dirty individual if so. Their marriage imploded yesterday, with both filing for divorce ... but is there more to it?

Just a few months ago, it was Shawn Southwick facing such allegations with a little league coach and D-list actor who admits "mistakes" were made."

Hector Penate, who coached the Kings' two sons when he wasn't trying to make it as an actor, cryptically said "one thing led to another" with Shawn.

Southwick denies anything went down, but the above quotes are Hector Penate's own, and The National Enquirer says King caught her red-handed.