You can learn a lot of things in life like how to tie your shoes, count to six, and skip a stone - those lessons might be easy. Learning to forgive might not be so much. Sometimes we let our hearts get in the way of potential by building walls and blocking people out, but that is not how we find rest and peace. Forgiveness is like spending money to make money; in order to move on with life forgiveness must happen. Whether that comes in the form of closure or the renewal of a relationship you must get yourself to a place where you can fully let go.
Forgiving doesn't always mean forgetting either but it does mean letting go of bitterness that can get deeply rooted in your heart. If your friend crashes your car you can forgive them, but you probably won't let them drive your car anytime soon. In the same way, if a friend breaks your heart you can forgive them but you won't be drop kicking your heart into their arms right away. It is okay to guard your heart, but it isn't okay to let your heart be hardened by bitterness.
Forgiveness has never been an easy task for me, I would rather say "it's okay" and then be a hater for life. This year, however, especially in marriage, I have realized that that logic doesn't cut it in adulthood. For me, I don't think it will every be easy to forgive but I need to give myself and others a chance before things get out of control and we allow bitterness to grow.
Cut yourself some slack, we are all human. Forgive and move on, allow your heart to heal, and always give yourself the opportunity to grow.