Crush --
At 50, you're far from "over the hill," quite far, yet I seem to detect a note of desperation and clinginess in your post. Understandable, since he's the reason you've moved, uprooted your life, and feel isolated, but...
I think your issues go far deeper than some stains on a bedsheet. By itself, they mean virtually nothing, but in context...that's where your problems lie. You're unsure of things already and this new "evidence" fuels your many doubts about the future and the smartness and desireability of this upcoming marriage.
You can marry this guy anytime; if it's "to be," then it will be. But questioning of this magnitude now almost guarantees severe problems for your relationship in the future. I'd say pull back, put the wedding on hold, get some perspective and collect your wits, rethink the whole deal. You're not in over your head yet, but easily could be if you move much farther toward a marriage. You don't want to end up here on this board in a year!
I don't agree that "it's better with his lies than not being with him at all." In fact, my strong sense is just the opposite. Around here, what you're describing is a guaranteed recipe for immense problems. In fact, those problems are already a part of your relationship, a big part. Are you sure you want to risk carrying them over into a marriage? Do you really think they'll get better afterwards? How about 99% odds against that improvement?
The wisest thing I've heard you say: "I know that I will drop-kick him away at some point." You've already made up your mind, now it's just a question of when you're going to move on that. Take all the time you need, but trust your gut.
Ammon