I suspect you aren't only bored but also depressed, because you feel like you're no longer useful or of much value to anyone. This isn't true, of course, but your feelings are understandable.
After all, for much of your life you worked hard to be a good mother (which isn't easy, especially as a single mom) and I commend you for that. But now your children are gone, and you feel like you're no longer needed. You aren't -- not in the way you once were. Even when your children call or text, or come home, you sense things aren't quite the same. And hard as it may be for you to face, that's the way it should be. Part of our responsibility as parents is to prepare our children to be on their own.
The real question I hope you'll seek to answer is this: What does God have in store for you now? God isn't finished with you; some of the best years of your life could be ahead of you. Open your heart and life to Jesus Christ, and then ask Him to guide you. God's promise is true: "I know the plans I have for you... plans to give you hope and a future" (Jeremiah 29:11).
What will your new life be like? It could involve anything: working with a local service agency, getting a job, visiting people who are lonely, etc. Many churches need volunteers, or are involved with groups that do; your pastor could connect you with them. May God bless you.