They are not bigger than you or more powerful than you. The ominous monster of pain that you have built up outside of yourself is a illusionary distortion. The reality is that the losses that you need to grieve belong to you and as such they are not bigger than you or outside of you. Those losses are a part of your life experience that you've chosen not to deal with or to integrate. Sometimes being just hurts.
Many people hold onto grief for various reasons.
There is risk inherent in everything in life. I believe the consequences of unresolved grief are much more painful than wading through the grief. You do not have to choose to be unhappy. You can free yourself. Change cannot take place until the pain of holding on becomes greater than the fear of letting go.