Once I had to forgive someone and found I really couldn't. I tried for five long years. I prayed, cried, struggled, begged God for help, seemingly to no avail. And then the answer came. I was reading in God's Word when the light came on.
I had been viewing myself as a basically good Christian. Nothing in my past seemed to me as bad as what I was struggling to forgive. The day the light dawned God opened my eyes to how He viewed MY sins. Suddenly my blinders were removed and I saw MYSELF as the wicked one, grateful that God could ever forgive ME.
Forgiveness has never again been the struggle it was. If we ask the Lord to help us see your own wickedness we will never again view the wickedness of others as worse than our own. We cannot help others when we think we are holier than they are.