Obsessive Compulsive Disorder (OCD) Support Group
Obsessive-compulsive disorder (OCD) is a psychiatric disorder, more specifically, an anxiety disorder. OCD is manifested in a variety of forms, but is most commonly characterized by a subject's obsessive (repetitive, distressing, intrusive) thoughts and related compulsions (tasks or rituals) which attempt to neutralize the obsessions.
http://www.wikihow.com/Overcome-the-Fear-of-Losing-a-Loved-One
As far as fear of your own death, that might be a different game.
If you haven't before, try praying for help through this battle, It can do wonders