You must allow yourself to feel these feelings, and accept the fact that you are normal if you are engaging in any of these behaviors and signs of grief. You need to allow yourself time to grieve because it is an important aspect in your healing.
If you feel the feelings and work through them, your grief will lessen, and in time, fade. The memories will always remain as sweet memories in the case of a death, or in the case of a divorce, very often bitter-sweet.
If you are severely depressed for too long a time, if you think about ending your life, or if you become so incapacitated that you can't function day after day, you need to seek professional help until you are better able to deal with your grief.
Seeking help is not a sign of weakness; rather, it is a sign that you want to live and move on with your life.