Grieving is a painful and tough process. No one can tell you how long the grieving process lasts. It depends on various things, such as the (emotional) connection you had with that one person.
Grief counseling can cover many different aspects of this process:
As a medium I can help and guide you during this process. Know that you never have to grieve alone! In my office, I have guided several people with this tough process. It may not be all wonderful, but grieving will be (slightly) more tolerable and lighter so that you can continue living!