That is a really, really great question.
The great news about Jesus can bring forgiveness to anyone. The blood of Jesus is enough to wipe away even the worst of sins. If you are someone who trusts in Jesus Christ, then there is now no condemnation from God - he has forgiven you (Romans 8:1). The Bible is full of people who have done all sorts of really horrible things (adulterers, prostitutes, murderers, extortionists), but who are accepted by Jesus (e.g. John 4:1-26; 1 Corinthians 6:9-11; Luke 23:32-43). Even the apostle Paul (who was one of christianity’s earliest and most ardent supporters) was someone who was responsible for violent persecution of Christians before he encountered Jesus (Acts 8:1-3) - yet Jesus fully forgave him. It doesn’t matter what you have done - Jesus can bring you forgiveness.
This can be something that is very hard to grasp sometimes, especially when you feel weighed down by guilt. But if God has forgiven you, then you have every reason to forgive yourself too. You have been washed clean. So does God want us to feel guilty about our sins forever? The short answer is ‘no’.
Does that mean it’s wrong to feel guilty about our sin? Well” it depends. The Apostle Paul talks about two different kinds of sorrow over sin:
“Godly sorrow brings repentance that leads to salvation and leaves no regret, but worldly sorrow brings death” (2 Corinthians 7:10).
Feeling sorry about sin is a great thing if it leads to repentance (i.e. turning away from sin). That is ‘godly sorrow’. But feeling sorry for your sins is a bad thing if it doesn’t help you to turn your life away from sin. This can often happen because we don’t really believe that God has forgiven us - so we need to keep reminding ourselves that he has!
It sounds like you want to repent, but you’re worried that God will not accept you. Rest assured: He certainly will! You can find forgiveness no matter what you’ve done. That’s why Jesus died!
Think about it. John wrote “For God so loved the world that he gave his one and only son, that whoever believes in him shall not perish but have eternal life.” God’s love for you is so deep that he did not spare his own son but sent him to die so you could be forgiven. Do you think, if you are wanting to turn back to God, that he would reject you? The answer is a resound NO! Jesus says all of heaven rejoices when even one person turns back to God (Luke 15:1-10)
Repentance is hard work, though” And you will need help. Keep praying that God will forgive you for your sins - not just the sins of the past but as you find yourself sinning each day. Keep asking God to change you to become more like Jesus every day. But you are not alone. When you turn back God in repentance, God himself comes and dwells with you by his Spirit. He is with you every step of the way, helping you to understand the bible, say no to sin, assure you of your salvation. The more and more you walk in his way, the more and more you become convinced of the rightness of that way.
It would be great to meet up with another Christian that you trust that you can be open and honest about your struggles with sin (past and present) - someone who will challenge you to remove sin from your life and encourage you to keep remembering we need to keep relying on Jesus every day. The Bible teaches us that we should confess our sins to others so that we can pray for each other and find healing (James 5:16).