I have this Christian guidance book called:
Everyday with Jesus | For New Christians
it has many advices and notes about living a good christian life, what to do and how to worship god. It's not just another man made book but when it says something and gives advice, it provides a prayer and bible scripture reference.
There is one page that talks about Forgive Yourself, so I'll post the things it says to help you.
Romans 8:33 - 34 and 38.
John chapter 1, Proverbs 18:14, Ephesians 1:6, Colossians 2:10
Prayer= I thank you Lord,that you have forgiven me all my sin. Help me now to forgive myself, and to lay down my injured pride at Your feet. Amen.
You really need to forgive yourself and Jesus/God has forgiven you, or it would feel like you don't want to accept it.
I'm so glad Jesus forgave my sins and addiction, everytime I look back I say: "I can't believe I was doing this and I did that...
" and I feel so glad and grateful that God forgave my sins.