How to let go of anger when someone is hurting you constantly?

We have a child toguether. When we divorced I had no means to support myself or her and I lost most of my custody rights. He puts barriers for me to see my child. I still don't have enough money or I am in the right place to get a lawyer, I am walking towards that goal but in the mean time this torture has been an ongoing pain for 4 years already. It makes me sick physically, mentally and emotionally. It destroys my life, my relationships. How can I forgive, let go of anger, let go of pain, how???? If he is keeping me from my own child! Please someone who can tell me how to think or what to do to regain my inner stability and peace.