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 hear you Martin! Been there several times, sigh. It's important and vital that we not allow ourselves to be a dumping ground for others. In the end people are going to do what they want to do. I agree with a post here that they require professional help.