wants me to spend as much time as possible with them
So tell her that you will settle for nothing less than 50/50. Tell her that since it is 50/50 no child support changes hands. Tell her that you will not pay alimony. Tell her that all other child expenses will be shared based upon percentage of incomes. And see where that takes you.
And if she is agreeable to everything above just let her go. Is she really worth the heartache that she has caused because of her affair. If she is worth it perhaps she'll come back. Trying to "force" her to stay just doesn't work.
Also, take a deep look into how you worded the quote above. I see that quote as an indication that you have not yet come to grips that you are as much of a parent as she is a parent; and perhaps more of a parent.