It is not impossible to forgive someone.
The only way we can is because God has wired us for it.
After recognizing this, the next step is to realize that you do things wrong, too. When we understand and accept this fact we are more willing to forgive.
See, the problem is we don’t think we’re that bad. Or, we would never do what so-and-so did.
If we would see we’re all broken – all on an equal playing field – this paradigm would make us think differently. The Bible states to break one commandment is to break them all. In God’s world, sin is sin.
It’s alright to be hurt. If you want to forgive, God will help you. Otherwise you will become bitter. And that will hurt even worse.