The worst thing that could happen is that you go to hell for the rest of eternity (according to some). Something less cruel but still harsh is that you possibly get reincarnated and have to experience the same life again in order to overcome your struggles. If not, I suspect you will become an earthbound ghost and won't be allowed into Paradise for p#ssing off your guides, higher self, and/or whatever forced you into this miserable life that made you commit suicide. But maybe if you're lucky you will be pardoned if the cause of your suicide was any of the more legit and noble reasons you mentioned.
Either way, most likely nothing good will happen so I wouldn't recommend anyone to give it a go unless you have a good excuse that no one in the afterlife would get mad.
People don't get what they deserve. They just get what they get. There's nothing any of us can do about it. - dr. Gregory House