I feel the same way. I have to take a sleep aid every night so I can wake up the next day to the same anger, depression, distraughtness and feeling of helplessness that we cannot get to these animals BEFORE they suffer. Some of the additional animal atrocities that come across my facebook is more graphic and disturbing than Care2.
I, as well, stay mentally and emotionally exhausted. If I didn't have three dogs and fostering two kittens I would contemplate driving off a cliff, that way it could look like my vehicle malfunctioned and not a suicide. However, God knows my thoughts and stops me.
We just have to step away from time to time, don't ever think you are not doing your part if you happen to miss a petition or sending an email or making a phone call. Most "alerts for action" will be repeated. Animal cruelty is an epidemic, and as hard as we try we can't address every single one, if we tried we would be awake 24 hours a day.