You had mentioned you had children for her and in exchange you wanted your sexual needs met?
I may have interpreted that wrong, forgive me if I did, but I believe both partners should have kids because they both want kids, not to make someone else happy or to get something else in return. I know you love your kids dearly, but I think going into a mindset like this can set you up for huge disappointment when it doesn't quite work that way. Did you and your wife discuss these expectations and reasons for having kids before getting pregnant? or was this this an expectation on your end of how things should be?
My sex life with my ex was not good. He was my first and he was selfish in and out of the bedroom, very critical of me out of the bedroom, and very closed off to talking about sex, he just expected it. I did my "wifely duty" but it was a duty. I thought perhaps I had a low drive. Now that I am emotionally fulfilled and loved and made to feel safe and unjudged(by someone else)it turns out my drive is off the charts (TMI,sorry).
My point being, I think my ex and I had so many uncommunicated and unrealistic expectations, or unrealistic ways of how to achieve our desires, we both failed.
We all start off thinking about how things "should" be when we really have no clue until we are in those life altering situations (such as having kids). I think we also forget how to achieve those things we want. What we think should work is not neccesarily how our partner thinks things should work.
What I am trying in my relationship now, which I notice is making a huge difference is communication. On all levels about everything. I was a poor communicator in my marriage for fear of my ex not agreeing and just leaving. Now, I say what I need, we discuss how we are going to get there. I'm not perfect at it yet, but I can see what a difference it makes.