subtle but enormous chasm...

In trying to find a solution for guilt, we have finally come to the realization that to get rid of this guilt requires more than we thought and find ourselves separated from forgiveness by a rather enormous chasm.

"Not all the perfumes of Arabia," said Lady Macbeth (Shakespeare) "can remove this spot." "This disease is beyond my cure," says the doctor.

I think that if we can only take the next step and say, "I am guilty of sin," then the answer comes suddenly -- "I have a Saviour for you."

He went to the cross to carry the penalty and pay the price. It was not cheap; it was God’s priceless gift of His Son to bear the guilt brought by the sin of the world.
There is a cost to forgiveness - this article outlines what the costs are for a husband who has been unfaithful to his wife, but could be equally true for an unfaithful wife as well - check out this amazing article that clearly spells out the cost http://newlife.com/the-cost-of-forgiveness/

Guilt is real and if left unattended it will be compounded by each self-serving effort of irreverence, pride, fear, dismissal of the moral, or the claim of innocence. With admission of sin, there is the start of genuine restoration, because guilt is first a vertical problem before it is a horizontal one.
God has been violated before we have.  That is why it is God’s prerogative to forgive first. Only the forgiven know what that feels like, to receive forgiveness, and that is why they then in turn are able to offer forgiveness to others when wronged.

Check out the words to this amazing hymn --http://www.luminarium.org/sevenlit/donne/hymntogod.php