God's grace is sufficient to cover all of your sins, no matter how bad they seem or how far you've strayed from God. But, once you confess them to Him and accept Jesus, it doesn't stop there. You need to guard your heart and mind in Christ Jesus, meditate in His Word daily, and continually grow in Him. Otherwise, sin will eventually work its way into your life. God can forgive anything you've done, but once your time on earth is up, the decision can't be changed. There's a point where it can be too late.