CONSIDER MEDICAL OR PROFESSIONAL HELP:
There are a number of psychological illnesses, which distort people’s thinking and let them see only negatives in life; this can make suicide seem attractive. Illnesses, such as depression, panic, alcohol problems, bipolar illness, schizophrenia etc. etc. can all change people’s outlook. It is often hard to convince a friend that their strongly-held viewpoint about how dreadful their life is, can actually be a symptom of illness. It is like your friend is looking at the world through damaged glasses, seeing only blackness and despair.
It can be very useful to persuade them that you go to a doctor or other professional with your friend, tell the doctor what has been said, and then leave the room so the doctor can talk to your friend and intervene appropriately.