@sally27 ,
Sounds like you flawlessly executed the first undoing of a complex entanglement. The question is what is the next move and what variables will possibly alter your next move?
If somehow, you couldn't have this new guy, would you want to be with your current husband? You mentioned how if you left your husband how it would affect him negatively. However, I think it would be a bigger disfavor to sacrifice your own happiness on the premise that it will make him happy.
I've been cheated on by every girl I've loved. They always wanted to protect me, to not hurt me, by keeping the truth concealed from me. Yet, when you love someone, I think the biggest fear I have is that they would be waking up each morning next to me and wishing it was someone else in that bed. I don't want love through a lie, and even though the truth will hurt me, it won't hurt me as much as it hurts knowing the person I love most feels caged or obligated to stay with me against their own happiness. I think if you feel the same way, you should consider that it is likely your husband does as well.
The main question is. Right now today, would you want to re-marry your current husband? If not, how many days backwards can you trace where you would have said no? Also, why not exactly? What changed from when you married him to now? Is it something that can be regained, or is it something that is simply lost?
If the answer is yes, then I would think trying to make the marriage work would be best.
The new guy: He said he wants some space/time. He obviously has a lot to think about, but trust me, he respects that you told him even though he doesn't like the news. What his final conclusion ends up being, may very well depend on what your next choices are regarding parts of your life that may complicate his if he were to be with you.
I suggest, do not make your next choice based on what the new guy will choose. Meaning, if he says he wants to try with you, you choose a divorce. If he says no, you stay married. Otherwise, the atmosphere betwixt you two will be "I left my husband for you! you owe me loyalty!" Which will make him feel caged.
Personally. From my perceptions. If the following is true, that you don't love your current husband and the love is irredeemable, I would get a divorce. I then would continue trying to pursue this new person very cautiously depending on how the air is between the two of us. I would accept the possibility that the person may reject my love and that I would end up being alone, but in that time I wouldn't let that person out of my heart until it is sufficed in my mind that there is no possibility the two of us could ever be together. In which case, my entire quest for true love would have to begin anew.
As far as the power couple thing, that is something that has no direct tie on the business of the matter. It is a decoration, an ornament, that does not affect the integrity of the inner substance. Like, a nicely decorated coffee mug having no impact on the taste of the drink. Do not let that hinder you to fear the truth. That would be a self-sacrifice for your friends sake whom only you will end up paying for in the long run, don't do that to yourself.
Last. I think you should try to figure out what exactly allowed you to have eyes for another person when you made a perpetual vow to have eyes for only one. This may be a self-flaw that needs strengthening. Only you would know your triggers or reasons. You say you weren't looking for this new guy, but maybe subconsciously you were because you were upset about something or something else. You didn't get intimate with him, so it must not be a sexual weakness as much as it is an emotional connective weakness.
Whatever the case, I think you should apply some love to nourish your own self to grow stronger in any place you feel it would be a weakness for someone giving all of their love to you. While at the same time trying to untangle this entire thing.
There are still so many questions that only you have the answers to, so I can't say entirely confidently what I think you should do when there are so many unknown variables to your equation.