Well, I think you have given yourself some good suggestions: meditate, journal, do free-form writing and burn it, remind yourself of all the things that are good and wonderful about yourself, the other person and the world, etc. It doesn't have to take a long time, depending upon how honest you are about what you are holding onto.

From my perspective, forgiveness is an energy release. You are releasing yourself from the uncomfortable vibration of a judgment you have made about yourself, the other person or about the world in general. The sensation is uncomfortable because it is not aligned with the truth about you or the other person or the world. If you identify the judgment you have made, then you can release it more easily. If you think a person "should" have done or not done something, you can work to change that to a preference rather than a "should." If you believe someone hurt you, you can begin to acknowledge your part in choosing to be hurt. If you are kinesthetic, you may feel the low vibration in your body and you can pull it out like a cord, or dance it out...

Check out the work of Byron Katie http://thework.com/en to work with the beliefs you hold around these past events.

Love yourself enough to let this go.

perhaps it is a question,
of balancing that believed
to be entitled from
the sender to receiver

Yes, it is possible to forgive someone and our own selves for past mistakes. Believe me you feel relieved and very light after forgiving. Sometimes it is not easy and is not done in a single go. You need to keep on working.

Meditations help raise your vibrations and make this process easy. There are guided meditations on forgiveness specifically.

Guided meditations help a lot! It is my personal experience. But rather than playing an audio for guidance, if you have someone live, it has a better impact. I provide free guided meditation sessions. I am not sure what timezone you are in. If you are interested, I can provide you with the details and help you out.

You do not have to accept the action that hurt you as acceptable or ok. Forgiveness helps you more then the person you are trying to forgive. You can love everyone, yet shoot an intruder who threatens your family. Peoples actions are often hurtful, but it is important to remember we are all part of the same existence. Created as part of the same whole. When you forgive you release your negative emotion regarding the event that occurred. I find it easiest when I am very hurt to release it to the planet. Picture yourself sending roots 30 feet down into the ground, and send that energy into Mother Earth. She can and will neutralize it. Then picture yourself drawing your energy back in clearer and cleaner with the pain relieved. You can repeat it as often as you need to. You are forgiving for you. The anger is hurting you, sapping your energy. If this person caused such pain in you, they don't deserve any more energy. Remember you are a powerful being and manifest what you think. The more energy you give your anger or sadness the more you feed them. The monster this becomes self sustaining. Feel the emotion, release it and let it go. Send love and receive it in return. That doesn't mean your a martyr, or a doormat. It simply means you love yourself enough to not perpetuate the cycle of pain. I know it's hard, it is for everyone. Sending you love.

Since you're searching for ways to forgive someone for past mistakes, I'd suggest you first ask yourself if you overcame the situation in which the mistakes occurred. Did you ?

If not, give yourself a little more time to work that out internally.

Otherwise, if you did, forgiving becomes realizing/deciding how much that someone (compared to their mistakes) is important for you at the present moment.

In the end, if that someone is more important for you than their mistakes, you owe it to yourself bringing them back to your life - forgiving is an act of love for yourself ;-)