brokendoll,
Life is tough and you don't have anything to repent of. You are doing the best you can. Jesus said the two great commandments are love God and love your neighbor. Marriage is not the purpose of life. The purpose of life is to learn how to love. Marriage is an important tool in the process of learning to love. Frankly, I'm not sure I know what marriage in the afterlife is all about. If I die my wife can remarry and when she is dead, we're all dead she could be sealed that that other dude. She'd have two husbands in the afterlife. When you are dead someone could seal you to all husdands to whom you were legally married. Joseph Smith was sealed to several women and many of those women were already married. It does not fit our ideal for marriage that we currently have. You don't need to beat yourself up over your marriage difficulties. Just keep trying. Be honest and try to love people. That's all that matters.
God wants us to be happy and he knows life is hard. That's why he gave us Jesus. I don't think God wants you to beat yourself up over your difficulties. Just try to love your kids, your husband and be happy.