Forgiving someone who hurt you can be one of the most difficult things you have done. When someone hurts you, they usually touch on something very sensitive in your life, so the pain penatrates deep inside and seems impossible to let go.
1). Ask God to help you forgive. Forgiveness is really an impossible task on your own. Some lighter things can be forgiven on your own, or with the help of counseling. But some things are just humanly impossible to forgive. Realize that and ask God to help.
2). When you ask God to help, you have to let go on your side. God will not forcefully take away something you don't want to give up. This can be extremely difficult, and will need practice.
3). When you can't forgive, thinking about what's at stake if you don't forgive can be a better remedy. Realize that unforgiveness hurts you first and foremost. It hurts you much more than the person who hurt you. It's like putting fire to your skin and hoping the person next to you feels the pain. Unforgivness will drain you of energy and will make you feel miserable. It's like a disease that keeps getting worse the longer you have it. It is in your own best interest to get rid of it as soon as possible.
4). Unforgiveness prevents you from enjoying life in the present and in the future. If you don't want to stop living, you have to forgive.