17Therefore, if anyone is in Christ, he is a new creation; the old has gone, the new has come! 18 All this is from God, who reconciled us to himself through Christ and gave us the ministry of reconciliation: 19 that God was reconciling the world to himself in Christ, not counting men’s sins against them. And he has committed to us the message of reconciliation. 20 We are therefore Christ’s ambassadors, as though God were making his appeal through us. We implore you on Christ’s behalf: Be reconciled to God. 21 God made him who had no sin to be sin for us, so that in him we might become the righteousness of God. 
The Holy Bible: New International Version. (1984). (2 Co 5:17–21). Grand Rapids, MI: Zondervan.
A friend and colleague asked a question about forgiving himself. His question came at a moment when I was thinking through the same issue. Responding to him helped me to find, for him, some thoughts that I needed to hear, and perhaps you will find these thoughts helpful:

To my troubled friend:

Forgiving ourselves is not a prominent topic of scripture

I think - and I am also working on this, rather intensely - that we should note that Scripture does not say much at all about forgiving ourselves. It declares that God has forgiven us, and urges us to forgive others. "The measure by which you judge others ..."(Matt 7:2) If we forgive others, we understand grace, and if we practice grace we can accept the grace which has been applied to our guilt.

You are not the proper judge of yourself (1 Cor 4:3-5)
But God forgives as the proper judge of our lives knowing our weakness and our wickedness. Judging us truly sinners, he truly forgives. I think it is a matter of faith and wonder to accept this decision of God, such faith being the alternative to the insistence on being our own judge - which is a sinful desire even when we 'righteously' condemn ourselves.
Trust God's ability to save those you have hurt (1 Peter 2:24, Isaiah 53:4–5)
I am also delighted that Jesus on the Cross offers not only forgiveness but healing and restoration - not merely to me, but to those I have hurt. The consequences of my sin are absorbed and inverted by God, in Christ, reconciling the world on the cross.
I am refreshed by the evidence of God's ability to heal - seen in my own life and in the evidence from decades of pastoral listening. The testimonies of the saints assure me that God is also able to lift my victims out of the snares I once set.
All that remains is for me to be attentive to God regarding any opportunity to be an agent of his reconciliation through prayer, confession to the offended party and/or acts of contrition and restoration as Jesus directs me through the Holy Spirit and the Word.
Lingering guilt does not lead to the right actions.(Psalm 38:4,Isaiah 24:20)
I am troubled that my guilt driven attempts to fix things and so redeem myself may very well cause further harm. So I try to defer, in faith, to God whenever I find guilt resurfacing.
We are not what we were before we turned to Jesus, though we are not yet all that we will be.
I, and you no doubt, can also testify that God has made and is making a new creation of us, This hope draws us forward, while the lingering fear that we will revert to our past ways is only detrimental. God deliver us, sainted sinners, from guilt and fear into grace and peace!