Guard your heart from becoming cynical or calloused because of all the tragedies and sad things you have seen, experienced, or have been involved with. (Proverbs 4:23)
Guard against becoming "Immune" to people's pain and suffering - it's healthy to feel and show empathy (1 Corinthians 12:25-26, Galatians 6:9-10)
Do what is within your power and ability to do. It's ok to let other people help. (Proverbs 3:27) It's also ok to say "No" so that you don't add to your weariness.
Establish healthy boundaries. If you are not sure how to do this, consider reading Boundaries by Dr. Henry Cloud and Dr. John Townsend.
Take some time to rest and be refreshed. Especially when you feel emotionally drained and have been walking through crisis and trauma.