Grieving is what happens when there are endings. When you have trusted your life to be lived in a certain way and then something happens to cause you to question whether it will continue to be lived that way, grieving begins to happen.
That is why a diagnosis is an occasion for grieving. If you have been able to be independent and self-supporting and then you are diagnosed with a disease that might compromise those self-supporting activities, you have to learn to live again in light of the new reality.
Because of this, we start acting in ways that we may not like. We name our losses and feel the pain of fear and anxiety that comes with uncertainty. We find ourselves getting angry at others, even those who have not had anything to do with our situation. We get angry at others who are not threatened like we are. We begin reminscing about days in the past when things were good. We look around for someone or something to blame and assign guilt.
But, for us to be free to live with our disease or our altered circumstance, we need to be freed from our guilt and our pain. Over time a forgiving spirit can emerge. I don't think forgiveness is something that someone simply decides to do. I think it is often a gift that comes to us when we work through our losses and when we gain strength to imagine new and different ways of being. We are resilient people and it is possible to discover new things about ourselves and new possibilities for our lives.
The emerging of new life can be terribly painful. Don't let anyone talk you out of your pain. But, find some friends to talk with about it. Shared pain can be more manageable. Explore your new new limits. See what you can do with the new reality. It is not easy but it can be redemptive.