Too messed up

I just read a question on ask a coach, where the client was concerned about being “too messed up” for this work. The coach replied that “the coach may suggest additional support if necessary”. This is a fear that has come up in my own coaching business- what if I get a client that I’m trying to help and it doesn’t work and they end up committing suicide? I recognize that this is my brain going to worst case scenario, and when I did some work on it yesterday I realized that I would make it mean I can’t do this, it’s my fault, I’m not qualified. I work with moms with depression- how do I know who this work is for and who it’s not?