I haven't read the other responses yet, so I hope I'm not repeating, but anyway…...
You have to understand that the intensity of your passion, curiosity, and interest in him will take time to die down. That kind of intensity, right or wrong, takes time to diminish.
In the meantime, however, you CAN do some things to keep from fanning the flames, as it were. STAY OFF of his FB page. Really. You must unfriend him, block him, and sever that tie COMPLETELY if you really want to get on with your life and reconnect with your husband. Unlike former high school boyfriends, with affairs, you CANNOT be "just friends." It's not possible for you, with your level of intensity, and it's not fair to your husband. So, right now, after you've read this, go to your FB account and unfriend and block. NO contact with him at all. Delete his number from your phone, if it's still there and take his email out of your contacts.
In addition, stop with the second-guessing of his motives. Could be anything, really, and realize that what he does has nothing to do with your life anymore. That's hard to accept, I realize. As you said, you shared "hopes and dreams" with him, but now you have to treat your relationship with him like a death. He must be dead to you.
I get that that sounds harsh, but IF you REALLY mean it that you want to stay with your husband and fully commit to him, start grieving this other guy so you can really feel internally that he is part of your PAST. As it is now, even though you live far from him, he is part of your present because you're making it that way.
If you have any mementos from him, get rid of them. Letters, emails, other reminders of the relationship----need to be gone. Your attention and your full presence must be with your real life, not with the fantasy of this past relationship.
When you find your thoughts drifting to him and your past, allow it MOMENTARILY; let yourself feel the sadness or whatever, and then immediately after that moment, think about the pain in your husband's face when he found out, think about how you gave away time to this affair that you could have given to your children. Do this every time you have thoughts of him. If you pair the fond memories with the current realities every single time, it will eventually become more unpleasant for you to dwell on him.
If you find that you cannot do these things on your own and continue to stay stuck thinking about him and allowing this to interfere with your present life, please seek professional help. No need to waste any more of your life on something that doesn't belong in it.
Good luck and hope you will soon move on from this.
J. F.