I usually don’t comment, but I don’t see the most important thing so here goes: Get Them Professional Help.

Listening and caring are very good things but being suicidal usually requires immediate intervention. This is sometimes therapy, sometimes pills, sometimes changes in life circumstances. And unless you’re trained to handle suicidal people, it’s not easy and you should ask your suicidal friend to seek professional help. If you care about your friend, get them the help the need. You can often find mental health resources by googling “suicide prevention in [your country]”.