Here's a devotional I was reading on this topic this morning. Take a look...it's very well written and layed out! I really enjoyed it.
Yes, you can and you must! Not next week or next month, either - you need to forgive that person today!
Spiritually speaking, unforgiveness is downright dangerous. It will make your spirit feeble and your prayers ineffective. It will pull the plug on your faith so completely that you won't have enough power to move the molehills in your life - much less the mountains.
Read Mark 11:22-25 and you'll see why I say that. There you'll find one of Jesus' most powerful teachings on faith. He concludes that teaching with these words, "And when ye stand praying, forgive, if ye have aught against any...."
Notice He didn't say, "When ye stand praying, try to forgive" or "When ye stand praying, forgive if you can." He simply said, "Forgive." Period.
Jesus made forgiveness a command. It would be unjust for Him to command us to do something we couldn't do. So you can be sure it's within your power to obey His command and forgive - no matter how badly you've been wronged.
Why then has it been so difficult for you to do so? Probably because you have fears that are holding you back. Most people don't realize it, but unforgiveness is actually a form of fear. Quite often we don't forgive because we're afraid of getting hurt again. We're afraid we're never going to recover from the damage that person has done to our lives.
If you want to freely forgive, get rid of those fears. Cleanse yourself from them by the "washing of the water by the word" (Ephesians 5:26). Fill your mind and heart with promises of God that apply to your situation.
If your business has been threatened by this person, for example, meditate on the fact that no weapon formed against you will prosper (Isaiah 54:17), and rely on the fact that your God will supply all your needs according to His riches in glory by Christ Jesus (Philippians 4:19). Let the knowledge of the merciful, protective love of God cast out all your fears (see 1 John 4:18).
Then forgive, not by feelings but by faith. Do it the same way you would receive healing or anything else by faith. First, make a quality decision. Determine that you're going to do what God's Word instructs - no matter what. You're going to forgive.
Second, speak and act in accordance with that decision. Refuse to say anything negative about that person. Refuse to rehearse in your mind or with your mouth the hurt they have caused you. Instead, look for opportunities to bless that person both in word and in deed.
Finally, don't be moved by what you feel. Forgiveness is an act of the will, not feelings. When lying symptoms of unforgiveness well up inside you, come against them in faith. Say, "Praise God, I have forgiven that person by an act of my will. In the Name of Jesus, I'm not moved by these feelings. They'll just have to get in line. They'll have to submit to the faith and the love of God that's been shed abroad in my heart."
If you'll continue to do that, I can assure you from my own experience, your feelings will change. It may not happen overnight...but it will happen. One of these days, almost without thinking, you'll throw your arms around that person, give them a big hug and say, "I love you." What's more, you'll mean it from the bottom of your heart.