Choose integrity - always. There's a lot more at stake here... Folks are watching you, your children are watching you. Your character and your integrity are in question. They are teetering on the edge of the cliff high above the chasm filled with shame and misery and death.
I'm sorry that in the years that you were together with your wife you have not learned to love her but I suggest you do so before the her that she is vanishes.
AD is not an easy disease on anybody but especially her.
To be quite honest perhaps she didn't want to marry you either but you took something from her that wasn't yours to take and perhaps she thought she was less worthy of a person because of it and she married you.
Regardless, you are married and that's what married means. There have been plenty of people throughout history that or married for reasons other than love and they learn to love each other. Besides, love is a verb it's not a feeling.
I've heard it said that the grass is NOT greener on the other side of the fence. I would strongly encourage you to refuse entertainment temptation and refused to join the other fools who thought the same only to find out it was indeed not greener, but instead full of death and misery.
I strongly would suggest that if you desire greener grass that you start watering your side.
I'm sorry to be so blunt but there's a hell of a lot more at stake here than just you satisfying your selfish lusts or whatever you want to call it.
I can't tell you how many people have gotten sucked in to the deceptive fantasy of an affair in search of what might have been only to come out the other side poor, blind, naked, and bleeding, having lost it all in the foolish decision to pursue something based on a whim.
You're a grown ass man and now more than ever is the time to stand up and be a man. You have no idea what that other person is really like but you have this blind fantasy about what you think she's like and that's how Affairs start.
The fact it she is even giving off the vibe that she might be interested in pursuing a relationship with you should speak volumes to you about her own character considering you're still married and your wife is sick.
Do yourself a favor and invest in your wife and your family. It will pay much bigger dividends.