That pretty much echos my feelings.
Several thoughts here; first, if Hank is boasting about his other "conquests" and you don't want to hear about them, tell him so. That doesn't have to be a morality issue at all; it's just a TMI issue.
Second, since Hank has made you privy to his dalliances, make it clear to him that you are uncomfortable being put in the position of keeping his secrets away from Dana. If he doesn't want Dana to know he's picking up other women, then he should not tell you about it, either, lest you inadvertantly say something that spills the secret.
Third, whether you tell Hank this or not, he has put you in the unenviable position of taking the heat when his indiscretions are uncovered. We had an engineer in our group a number of years back that was cheating on his wife. He would tell her he had to work overtime, or that he was going to play golf with his co-workers, and then meet up with the other woman. We had no idea we were supposed to be his alibi (and I would not have agreed to cover for him anyway), but when his wife found out, she still was angry at us because she thought we DID know and at the very least condoned his behavior by helping him to hide it.
It would be nice if the consequences of our actions was restricted to ourselves, but that is rarely the case. By his actions, Hank has placed you within the blast range of his actions. When things "blow up", which they most likely will eventually, you and your husband are going to catch some of the shrapnel from it. I hope Hank's friendship is worth it, because you could very likely lose other friendships in the fall-out.
