I have a super-depressed friend messaging me right now, but I have also had to learn not to be "reflex rescuer" and allow others to steal my joy and spread their misery. I am allowed to have quiet time in the evening to process some photos. There are helplines if you are suicidal; I can't take it all on my own shoulders.
I have had to let go of some people in my past because I realized I was enabling them, and they were destroying me in the process.
It takes courage to let go. It is not easy sometimes.