My husband isn't cheating that doesn't mean he hasn't thought about it. That I do know because he has told me he has considered it. He even went to say he thought about sleeping with someone else just to hurt me but he hasn't. With everything else he has been honest with I can't see him lying about whether he is cheating or not.
Considering he has a history of cheating, he could be gaslighting you here... He seems manipulative enough to do this...
As far as not sticking you with bills, if he gets the motorcycle or truck, and still divorces you, how do you know you won't be expected to pay half the debt?
Be super aware of what can happen here. I know you think you know his character, and what he is not capable of, but I think you are seeing him through rose-colored glasses... Walkaways and waywards often resort to behaviors the LBS could never fathom... You are too hard on yourself and not hard enough on him...