I just wanted to encourage you and let you know you are not alone. I was married in the temple, but my husband left the church after about two years. It was hard, and I'm sure you know more about what that little word means than I need to express, but we finally came up with an agreement that since he knew he was marrying an active Mormon he must allow me to raise the children in the gospel. Then I prayed a lot and loved him a lot. I still shared a lot with him, just not very much about the gospel, yet it seeped in. I then sought preisthood blessings and had many special experiences and was told that this was my husbands trial, but that he would come back into the church while I was still raising my children. This then directed my path and my decisions-I simply lived life as if he would come back soon. About eight months ago, eight years from when he left, my husband struggled and we struggled and he reached a place where he was willing to pray and follow the answer. We were blessed with experiences so strong over the course of two and a half weeks that he prayed and asked God to slow them down, because his physical body was so exhausted. My husband is now actively striving to follow God, which at one point looked impossible, but God is faithful, I promise you He is, and God will keep what ever promises He makes to you through preisthood blessings if you are faithful. His promises to you will be different than the promises made to me, but get them and then rely on them.
We are in a fight, a war, in fact, but the blessings of God will far outway all of the trials, the turmoil and the heartche that we experience now. He'll bless you as you teach your precious sons and then, who knows, those sons may be an instrument in softening the heart of their father and grandparents.
As far as studying the gospel with your children I, too, have used the plan from this link http://www.schoolofabraham.com/storiedscriptures.htm. I find it best to just read and talk and let the discussions and the spirit take over. The children often ask questions and we talk. It really is that simple. We sing primary songs and sometimes read the Friend. We also have at least one religious book that we are reading aloud going all the time. Our Favorite was "My First Mission," by George Q. Cannon. The Gospel Doctrine lesson manual is good too. We have also gotten the "Faith Preceeds the Miracle" by Ezra Taft Benson on Audio and listen to it when we run errands. I personally love the surety and examples in this book.
I pray to God that you feel the Savior take the other side of the yoke as you do what you are feeling called to do.
Melissa, Mom to 9yos, 8yod, 4yos, 3yos and 1yos