WorkinProgress,
I don't think those thoughts are a waste at all. I believe it is a part of grieving until we make peace and accept the loss. I don't think you are going backwards. You had hopes and dreams with this man. You lost that to his alcoholism. I'm sorry for that. Give yourself permission to be sad.
This might sound crazy but accepting those thoughts and letting yourself feel that loss will actually help you heal. You also move on to other thoughts and priorities faster when you accept what you are going through instead of battling and "shoulding" yourself.
I wish you peace within and healing, one thought at a time.
Love,
Lily