I've experienced that terrible kind of pain grieving for family that have died but oddly, my suicide as a concept has long felt reassuring- like a backup plan if/when I don't want to cope with life anymore...
Of course, the reality of actually going ahead with it is something altogether different. I think the most common emotion I have around it is frustration.
Up until now and until my Dad passes, it's been a frustration that I couldn't do it to him- it would devastate him. I reckon it may still continue afterwards though because I don't know I'll ever pluck up the courage to do it.
Plus, there's the frustration we all share that any attempt isn't easy, could fail with dire consequences and no one knows what happens afterwards. I guess the frustration can get so intense that it hurts, although it's not really a sadness for me.
I guess I've had suicidal thoughts for so long now (32 years) that they are no longer frightening or sad but part of my normal, everyday thinking.