If you are thinking God still holds on to your past sins. And maybe when you hit the floor to pray satan rolls back the images, the scenes, the incidents, then you get weighed down in guilt and stop praying, and stop fellowshipping, feeling unworthy. You are doing exactly what he (satan) wants you to do. God has forgotten your sin, immediately He forgave, He forgot. The moment you repent and ask for forgiveness, He forgives and forgets. Do not fall for the guilt offer of the enemy. Lift your head on high and walk in the newness of life that God has given you.
Even if you fall, right in that fallen state if you cry out to Him for mercy, He hears and will abundantly pardon. THIS IS NOT TO SAY YOU SHOULD MAKE A PRACTICE OF SIN.
But hey! If you are forgiven then you are free from that sin and guilt, whenever the enemy shows you the sin show him the blood. Let Him know that God is strong in your midst and He is having a party in your honour right this moment.
The Lord your God is in the midst of you, a Mighty One, a Savior [Who saves]! He will rejoice over you with joy; He will rest [in silent satisfaction] and in His love He will be silent and make no mention [of past sins, or even recall them]; He will exult over you with singing. Zephaniah 3:17 (AMP)