I think that as long as there's no self-pity involved, one may think about suicide. If it helps You to stay true to Your decision, it's good. However, like Resident Bipolar brought out, You should probably take caution.

I usually try to avoid thinking about direct ways to kill myself (these tend to trigger some unfavourable actions). Nevertheless, I do often think about how it would be not to be here... It's sort of like stepping out of myself and hoping I would disappear. I wouldn't mind death, but not really going for it either.