Being a single parent is surely one of life's hardest responsibilities -- and I want to assure you that God knows the burdens you face. He also knows what you can and can't do -- and He doesn't want you to feel guilty because you can't spend long hours praying or reading your Bible.
But He does want to reassure you of His love every day, and He also wants to guide you and encourage you. And this is why He has given you the privilege of prayer, and of the Bible. Don't think of them as burdens, therefore, but as gifts, given to you by God to bless you and help you.
The key is to realize that God is always with you, and you can turn to Him in prayer at any time -- even while you're getting ready for work or driving your children to school. Find time too to turn to the Bible, even if it's only a few minutes at first. Job said, "I have treasured the words of his mouth more than my daily bread" (Job 23:12).
In addition, do all you can to point your children to Christ and His love for them. Thank God for your food when you sit down for a meal; get a children's Bible story book and read it when they get ready for bed; make sure church is part of your life. Most of all, ask God to help you be an example to them of Christ's love and joy.