Suicide is the deliberate taking of life.
Suicide IS murder, murder of one’s own life!
This is just my opinion, but I think your idea of God is slightly off. My understanding of God is not one that He requires a doomed man to suffer needlessly. At worst, I suspect He would show them if they held out for a moment more, deliverance would come, but I don’t think He would vehemently condemn them for being unable to suffer more than they did.
Also, Jesus was sinless. He said Himself that no man could take His life, but that He gave it Himself. Thus, Jesus killed Himself. Did He sin by taking his own life?