Thanks for bringing your question to JustAnswer.
I am so sorry for the pain and anger you're experiencing after losing your son. While I understand that you want something to take the pain away, Xanax is a poor choice. It is highly addictive. If you are convinced that you need an anti-anxiety medication for a short while, Klonopin would be a better choice, as it is a little less habit-forming. The only medication for anxiety that isn't habit forming is Buspar.
But honestly, no medication is going to make all this go away. You need a safe place to express the anger and pain you're experiencing. A bereavement counselor or grief group is going to help you get through this mourning in the healthiest way. Call your local hospice (even if they were not involved with your son) and ask about help with your grief. The government requires hospices to provide help for people in the community as well. It can be so comforting to be in a room full of people who know exactly what you're going through..and you can express yourself no holds barred.