Grief can evolve into depression 

Symptoms of Depression:

~Constantly feeling helpless
~Inappropriate feelings of guilt
~Withdrawing socially
~Inconsolable crying spells
~Suicidal thoughts

If you're experiencing any of these symptoms, and  these feelings are interfering with your ability to function, it may be in your best interest to get help. If any of these feelings jeopardize relationships with family seeking help may also be needed.
Start by visiting your primary care doctor to discuss your options.