Part of the myth about suicide being a ticket straight to hell was propogated by the RCC long ago because people in fear of losing their salvation, who lacked faith, understanding and didn't think they would measure up, `According to works and sacraments would commit suicide after recieving "Holy Communion". (a shortcut to heaven in order to avoid hell) In a convoluted way they connected suicide to the traitor Judas Escariot (whom everybody hated) and declared it a mortal sin.
This is similar to the teachings of Eastern Orthodox that I am more familiar with. They severely stigmatize suicide and ban priests from being present at burial to say the last prayers with the family. I have two family members who attempted suicide (but thankfully survived at hospital with some body damage) and I have a history of suicidal depression myself. I hate the idea of suicide because I don't believe it's the solution. Nobody actually wants to die, they want to live free of suffering, so I usually begin with that when talking with suicidal people, and they do invariably acknowledge that. So I am not a denier or invalidator of mental issues like some people are. But there's still a shred of control we have over mind as compared to body, even when the mind is in a horrible condition. I would be careful in pronouncing condemnation, not just for suicide but about anyone. Only God knows our status, ours is to try by love to prevent suicidal depressed or other mentally ill people from leaving us and help them to manage their condition if it cannot be healed. People want to condemn but they do not want to learn how to provide support, they stigmatize and avoid people who are mentally ill. Maybe being more loving would help them push through and make life a bit worthwhile??? Just a thought.