I’m so, so sorry. This discovery must be devastating for you. You’re probably right that there is a connection of some kind between his past and his activities. Sometimes people who have been abused conclude that there are only two roles in the world: victim or abuser. Not wanting to be victimized any more, they take the other role. It’s a shame that your husband didn’t stick with therapy long enough to learn that there are other alternatives.
As sneaky and inappropriate as his behavior has been, he does seem to have some control over his impulses. He apparently has confined his activities to people over 18. That takes some self-control. He is apparently self-aware enough to understand that there are legal consequences to crossing the line of age of consent.
As painful as this may be, I think you need to ask your children if he has ever touched them inappropriately, just to be sure that he hasn’t reenacted his own abuse in the family. It isn’t necessarily the case but for your children’s sake, it’s important to check it out.
If you think he could be victimizing younger people, I suppose you could tell him of your suspicions to see how he reacts. Do be sure to have such a conversation in a place where you feel safe. Unless you have more than your gut feeling to go on, there probably isn’t anything else you can do about his psychological health or his behavior.
Instead, focus on making a good life for yourself and your children. You now have the opportunity to find someone who can give you the love, affection, and sexual connection you’ve longed for for many, many years.
I wish you well,