GUILT is about self-blame. It is often what I call misplaced responsibility, which involves taking on the burden of a negative event(s) that is really somebody else’s responsibility. For example, if you are robbed late at night whilst walking along a street in an unsafe neighborhood, you may blame yourself saying “I should have known better. I deserved it.” However, even though you might have been able to make a different choice about going to that place at that time, you are not responsible for the mugging – only the mugger is accountable for this. If you continue with this type of thinking you will feel shame that will lead to unworthiness. As a result you will unconsciously create all sorts of negative life situations believing this is what you deserve. This is a form of self-punishment.
You may feel GUILT in relation to a wrongdoing (e.g. if you are the thief mentioned above). In this case, it is best to make amends (apologize, return or pay for what you have taken etc). You will then experience what is described in the next paragraph.
FORGIVENESS is usually about self-forgiveness. Sometimes it is about forgiving others who have harmed you. This involves your acceptance of people/things (including yourself) as they are and the understanding that certain events happen for a reason. Compassion is often something you are told to feel for others in order to forgive but it is usually more beneficial to feel this for yourself. This will lead to many positive things such as, making it easier to forgive others, to feel at peace and to be happy.
An excerpt from DIY Therapy Chart: an Emotional Healing Guide.