Forgiveness

I have read many times that the reason we often get stuck in life is that we can't forgive those who have hurt us in the past. After all, the one who hurt us either isn't aware, or doesn't care about it, so why give them the power to control us?
This makes sense, and I try to forgive those from my past.
Just today, I started to forgive an ex-boss. It started out like this:
Marie, I forgive you.

But then it quickly became:
Marie, I forgive you even though you are a worthless miserable piece of excrement and I hope that you are dead by now, so that you are deep within the bowels of hell. You made me feel awful on a daily basis and partly because of your evil nature, my life sucks. I hope nothing good ever happens to you or anyone in your family or anyone in your life. May you suffer 10 times what I did for 10 times as long.

I think I need to work on my forgiveness skills a bit more.