The Stages Of Grief

I was just reading about the 5 stages of grief...


Denial and Isolation:
At first, we tend to deny the loss has taken place, and may withdraw from our usual social contacts. This stage may last a few moments, or longer.

Anger:
The grieving person may then be furious at the person who inflicted the hurt (even if she's dead), or at the world, for letting it happen. He may be angry with himself for letting the event take place, even if, realistically, nothing could have stopped it.

Bargaining:
Now the grieving person may make bargains with God, asking, "If I do this, will you take away the loss?"

Depression:
The person feels numb, although anger and sadness may remain underneath.

Acceptance:
This is when the anger, sadness and mourning have tapered off. The person simply accepts the reality of the loss.

I seem to be stuck. It's been 4 years since my Mom died and I'm still mostly angry with her, though I also get very sad and depressed. So I guess I'm going back and forth between Stage 2 and 4. When will number 5...the acceptance kick in? How can I learn to accept what has happened?