Life can be a lot to bear. I take comfort in knowing that what shows up is what we have room for.
Personally, what has helped me are three things:
~ Regular acupuncture, preferable from a Five-Element Practitioner
~ Some sort of internal, daily practice - i do Sufi Remembrance every morning, with some other sitting practices, and qigong - this is 30 minutes to one hour every morning i spend on myself, refilling my cup so i have more to give. Seriously, i will wake up at 5 am if need be to get this in. It is critical to my well-being, and i think it is missing from a lot of people's lives.
~ Some sort of external practice - i do light jogging/walking and weight-lifting mixed with taiji. As an (student) acupuncturist, the Liver (think of the energy of the Liver, not just the organ) is responsible for the emotion of anger; the Liver also likes movement - therefore anger gets processed, partially, through movement. I also eat as clealy as possible so the body can focus more on healing, less on digesting animal protein and processed garbage. What this looks like specifically varies from person to person.
You are comprised of a body, mind, and spirit. Emotions affect people on all levels, so you have to be very proactive *on all levels* to not let emotions hemhorrage you. Seriously, just go through the motions at first - lovingly forcing yourself to tend to yourself.
What makes you happy? When are you joyful? Healing happens when you increase joy in your life. Make joyfullness and lightness a priority - schedule it in!
I cannot stress the importance of having a spiritual (or internal) practice. What has helped me significantly are the Sufi healing practices of opening your Heart: http://www.sufiuniversity.org
If this does not speak to you, every culture has a spiritual healing practice - find what does speak to you.
One of the practices include opening your Heart through meditation and putting these strong emotions into your Heartspace - something that i'm finding near impossible to convey through this medium - as long as your pain is 51% Heart, then you're healing versus hemhorraging. Set a timer if you need to for 15 minutes or so, really focus on opening your Heart to the anger and the custody battle, cry, whatever, and when the bell goes off, then go about your day. By working on it diligently, bit by bit, your Heart will begin to soften the anger.
And don't be too proud to get help - i love acupuncture, and an acupuncturist can be a great help to move energy in your body (emotions are qi in motion). Like i said, not all acupuncturists are trained the same. If you're fortunate enough to live somewhere developed, then perhaps you have a Five Element acupuncturist nearby. Regardless, any body-work healing modality helps if you ressonate with the practitioner.
Lastly, the Chinese character for "crisis" is the same character for "opportunity." In what way is this situation a blessing? Can you create a bigger story of this custody battle, one that's big enough to live in? Perhaps the way you're holding it now is a killing story. Please be gentle on yourself.