One June evening in 1996, I was almost left without a father. My dad was deployed in Saudi Arabia when the barracks next to his was bombed by terrorists. As I think back on that night, though I was quite young, I'm grateful that my dad was not among the 19 killed in action that night. While our culture doesn't put a premium on the impact that a great dad can have on a kid's life, the fact remains that no one can take your place. You're uniquely and perfectly suited for your wife. Your marriage is the most important relationship in your life, more important than that of yours with your children and more important than your relationship with your parents. Certainly these relationships are in a very close second place, but nothing will ever be as important as your marital relationship. It's the spring from which blessings flow, and no one can take that place of honor.
You loved your children first. You're their father and they need your unique gifts. More than that, they need your guidance, your firm discipline, and your tender love. Their mother is able to offer them love and gifts in her unique way, but they also need to receive it from you. In that way, you and your wife compliment each other, providing for your kids in a holistic approach. Since you're irreplaceable, you need to act like it. Be involved in their lives. Be present in all ways: physically, emotionally, spiritually. If no one can take your place, then it's up to you to do your best to meet those needs. Rise to the occasion, and be an awesome husband and father.
The role of husband and the role of father aren't for the faint of heart. Stand up and do something.