Have you sinned so much, so badly and so frequently, that you feel God no longer has any grace or forgiveness for you?
If you have faith in Christ and trust God’s word, then you are thinking too little of the cross and too little of God’s grace.
The Christian cannot out-sin God’s grace. It was not merely a portion of your sin that was placed on Jesus Christ. All of your sin was placed on the cross. When Jesus died and rose from the grave and conquered death, he conquered all of your sin. Jesus bore all of God’s wrath that you deserved.
You are right to think that you have sinned greatly. You have. So do you see how amazing the cross is? Do you see how great God’s grace is?
Therefore, go and sin no more.