“There is in every true woman's heart, a spark of heavenly fire, which lies dormant in the broad daylight of prosperity, but which kindles up and beams and blazes in the dark hour of adversity.” ~ Washington Irving

When you hold on to a grudge, or regret, you are holding on to negative emotions that can block you from manifesting good things in your life.
To remove this block, You need to forgive and let go.
Forgiveness doesn't mean that what the person did was OK. It doesn't mean you have to trust that person or let them hurt you again. It is wise to not allow yourself to be hurt again.

Forgiveness means letting go.

Let go of the pain and resentment you are holding onto.
Accept that what is done is done. You can't change the past. But you can change how you feel about it.
Holding on to the pain hurts you. Reliving the hurt over and over again only hurts you, it does not bring you justice, or protect you from being hurt again. It doesn't bring justice to the person who hurt you. Don't let them hurt you any longer. You can decide to make it stop.
Everything happens for a reason. The things that hurt you in the past happened to teach you something, or to make way for good things to happen, or to cause you to grow. If you have learned from them, you don't need to fear it will happen again. Decide to feel grateful about it. Not about the hurt, about the blessing you received through it. If you are not sure what the blessing is, you may just have to trust that there is one, and you will find out later on.

Try this truth exercise, it may open your eyes:

Write down the times in your life when you were really hurt, your most painful experiences. From way back when you were a baby all the way until now. Just stick to the main ones for now, so you have about 5-10 experiences. Leave a space next to or under each one for more writing. Go over each experience and write down any good things that you learned, any good things that the event led you to, how you have grown because of it, and any other gifts or blessings you can think of that it brought you.

When I did this exercise, what I found on that piece of paper was everything that made me who I am today, and the things that shaped my best qualities. It blew me away. I saw that it was all for a reason and I felt grateful for it. I wouldn't have become who I am any other way!

“If we study the lives of great men and women carefully and unemotionally we find that, invariably, greatness was developed, tested and revealed through the darker periods of their lives. One of the largest tributaries of the RIVER OF GREATNESS is always the STREAM OF ADVERSITY.” ~ Cavett Robert

Forgiveness meditation:

Find a quiet place by yourself.
Think of the memory or person/event that hurt you.
Imagine it is a ball of energy, and observe it. Where in your body is it? what colour is it, what shape is it?
Imagine it coming out of your body, and hold it in your hands. Imagine it is now separate from you. See it as not being part of you.
Now say to it: "Thank you for the gifts you have given me, and the lesson's I have learned." (say what they are), "and I now choose to release you."
Now let it go! Imagine it floats away into the universe, and it disappears.

Author's Bio: 

Melissa J Magnus
Cert. Life Coach, NLP Practitioner and Law of Attraction Practitioner.
Empowering Mothers at http://www.lifecoachingformothers.com