@sally27 ,
Perhaps because your now husband forgave the cheating, listening to you that it was just physical but you have emotional attachment to him, he asked you to marry him, become exclusive, forget the past as marriage is different than girlfriend and boyfriend.
I'm not sure what he did wrong you didn't say.
Maybe you felt that you didn't want to lose him so not cheating on him being married instead, wow, what an emotion, togetherness, yeah it's time.
But, it's not in your nature from the sounds of it even if this guy turns out fantastic, you'll find you will find him non attractive at some point as well, not physically attractive and won't want sex and will be looking elsewhere "again" for that connection.
Some people and I say people just love lust and what comes with that, the new budding love, or they miss something and get it from others but they don't know how to just be with one person though they try.
I'd say your husband asked you to marry him for a reason. He loves you. 7 years is a long time. He forgave you.
Power couple suggest money, success. It's not an impossible task to leave anything if you're not happy. But, how do you know this "lust" that you call love over a real short period of time, won't fizzle? Then you are left with nothing.
Your Husband forgave your past actions. I don't think he may forgive you this time but you OWE it to him to tell him, just like you did before. This guy put a ring on it, wanting exclusivity and togetherness. You owe it to him.
Meanwhile this other guy thinks you're single once you tell him, he will be gone or I would be if I was a male. Deception is not something to trust.
You know the story you can't have your cake and eat it to.
Maybe you really aren't ready to settle down. I think you "think" you are in love with this guy but you are in love with the fact that he offers more brings more to the table than any other man you were with did and you have been with your husband for 7 years and maybe married him through excitement of the idea, time spent together, his forgiveness, your success together he's a "nice guy"... Not worth losing. But you may very well do so.
Time to just take what happens of what you created but also more so, look into why you can't settle down because you honestly can't and nothing is going to change that when the next guy comes along.