It's quite natural for you to feel bitterness, but you have to move forward. This is from my post of affirmation yesterday - it was only a test, but this bit may offer you some encouragement.
God's love changes the way I think and feel. His love washes the toxic waste out of my mind and gives me a clean mind and a pure heart. My old way of thinking and feeling is gone. My mistakes and failures are cast into God's ocean of love. For the first time in my life, I dare to call God my Father and live as one of his children. God's love heals my damaged emotions, and my negative feelings and guilt are washed away in a tidal wave of love.
All those negative feelings will go away when you're ready to let go and move on with your life. I think God gave us tools to deal with loss, I think that is the mourning process. Anger is part of that process - just try not to get stuck there and do hang in, you're feeling anger for a reason. You just a suffered the loss of a loved one.
I heard once that divorce is harder to accept than death because the other person made a choice to leave us. But we still have to accept and move forward. I'm just comforted to know that I have been given the tools and that these feelings will lessen and finally come to an end.
cb