So far, you've tried to live your life without God and to be honest, where has it gotten you? The Bible warns that "the way of the unfaithful is hard" (Proverbs 13:15) and I'm afraid your life is a tragic illustration of this truth.
Why, then, leave God out of your life any longer? Isn't it better to face the future with Him than without Him? Isn't it better to turn to Him for the strength you need, rather than rely on your own strength? I think you know the answer. The Bible says, "A fool finds pleasure in evil conduct, but a man of understanding delights in wisdom" (Proverbs 10:23). Don't stay on the path you've been on any longer, but turn from your sins and open your heart and life to Jesus Christ.
Why do I urge you to turn to Christ? First, because you need Him right now. He loves you, and He wants to come into your life to forgive your sins and set your feet on the right path. He'll also give you strength to resist temptation, and to live the way you should both now, and when you leave prison.
But you also need Christ for the future. One day you will die and enter eternity but what then? Make sure of your eternal salvation by trusting Christ and what He did on the cross for you. Don't let your failures keep you from God, but commit your life to Christ today.