To be totally honest, attraction and infatuation are not always one in the same thing. Thing is we are all "attracted" to other people, we can find others of the sex we are interested in and it doesn't have to lead to infatuation.

This is what I see. You mention that she was your first, your wife.

You've talked of divorce and you mention ups and downs. If you've gotten to the point of talking about a break up there is something missing in your relationship with your wife that you are seeking and you likely see something in this other woman that would probably fulfill this - in your mind anyway, even if it's not conscious.

I don't know where you are in your marriage but the fact that you let yourself be infatuated with another woman speaks volumes. I know you think and feel it can't be helped but I would venture to guess that if everything in your marriage was great you probably wouldn't even have any interest beyond noticing a woman might be attractive in passing. That is where I would look into yourself first.

What are you missing? find out and decide at that point what you want to do... approach your wife about it and reconcile whatever it is, or some other thing like moving on. I'm not encouraging either choice I'm just saying it's one that you have to consider. Don't approach the woman you are infatuated with, approach your wife, first. The temptation with this woman would probably be to high and that would be playing with fire IMO.