If your wife has the right to claim the children & since they lived with you more than 50% of the time, you can claim them. When you enter their information, they are considered your children. For your AGI, it depends how you filed in 2017, if you filed a joint return in 2017 then you use the same AGI for both of you. If you did not file a joint return in 2017, then use the separate AGI from each of your 2017 returns.
