Have you ever watched a scene of someone drowning and flailing around for help but there is no one to help? Suicidal thoughts come in those moments when someone can't find a way out. It's an abyss that they are looking into, or should I say surrounded by it.
Someone else said that committing suicide is easy. Heck no. Killing yourself is the hardest thing that you can do because we naturally are built to fight for survival, not for killing ourselves. When someone decides to quit, it means they have lost every shred of hope.
The thoughts are from helplessness, being stuck in a situation for so long, that you begin thinking that to make anyone happy around you, to find a single moment of relief, it would come from leaving.
Those who are able to fight it have to show incredible strength. When all that chaos is going on in your mind, when everything has turned against you, and you are still clinging onto that thin dangling thread of reality, that's strength.
If someone calls these people weak, they don't know what they are talking about.