Ultimately, you and your wife are meant to be a unit, taking decisions together in support of each other, but also ensuring that whatever you do, you put the children at the heart of those decisions.
What you feel is real, and needs to be discussed openly and as supportively as you've communicated to us, with your wife. There are the objective elements, and then the emotional ones. Perhaps, she's never thought that you feel this way. It may be because the Spanish culture is all about communicating; sometimes sharing a lot more emotionally than a Nordic / Northern European would.
A year away from her work which she has built up may be untenable, especially if her job is linked with her identity.
I put myself in her shoes, and if you had this opportunity, I'd want to know how we can make it work so that the family is together as much as possible, where possible. Ie: transatlantic flights, the ability to work remotely (for both of you, separately, to support this), children having all their hols in the US, and family support to step in for the role you've been covering, with a finite time for the project. Perhaps, once you've had the discussion of how you feel, and what she'd feel if the roles were reversed, on all of these elements, you (both) will find a way to make things possible.
Discuss visiting your family (ensure you discuss role reversal, but also cultural differences if this is what stops her from visiting...and probe core reasons and save them. Together), either in discussing your overall feelings (including how you love her and your life, but a small number of things would make it all so perfect), or an entirely separate discussion. Communication is so key, but also discussing feelings, expectations, hopes and dreams.