I only read bits and pieces of the thread but it seems the issue is still unresolved.
From a guy's perspective, Myway, I've read enough here to conclude that he's lying, no question. Many guys will deny something even in the face of cold hard truth because that's just how they were brought up. What kind of person is he? How much do you really know about him? Questions to ask yourself. It already sounds like he got caught up in a lie with the lost ex's panties/flooring incident, and yet he still denies it.
Weigh your options. Once you know he betrayed your trust, you have to decide whether you're better off with him or without him.
It might be a little different if he at least manned up and admitted the truth.