I am now doing some plaintiffs PI work and commercial litigation, but prior to going into private practice I was a prosecutor and specialized in Murder cases, including cases where I was seeking the DP. I can relate to the sleepless nights while in trial and anxiety waiting for a verdict.
As for the suicide stat, I think suicide is more a function of the intersection of people with mental health issues facing external factors (be it work, family, financial, etc) that they feel they cant cope with. Lawyers, plumbers, teachers....I don't think one profession is more prone than another.