We incarnate with a plan and with a whole host of spiritual helpers to get us there.
When a person commits suicide, they derail the plan. Regardless of the "pain" or "suffering" you undergo, it is a part of the overall life plan.
To choose to end your "suffering" you're choosing to end your lesson - almost certainly before you've reaped the benefit of it.
Your life is not designed to be "easy". It is designed to teach you that which you need to understand - not just in an intellectual way, but in a visceral, REAL way - about existence and Spirit.
If you want to be strong, you must bear burdens. If you want to be humble, you must be humiliated. If you want to be patient, you must wait for that which you desire. If you want to be merciful, you must find no mercy for yourself.
This is true in this life and doubly true on a spiritual level.
When you commit suicide, you fail to complete your obligation not only to yourself, but to the rest of the Universe with which you've made a pact. Your responsibilities and obligations get shifted to someone/something else and you are left with a spiritual debt. Some call this "Karma."
Until your debt is paid and you accomplish fully that which you agreed to do before incarnation, you will not move to the next level. If you cannot accept this understanding of things, then not only will you not move to the next level, you will be unable to reincarnate because you will be unable to break the bond that ties you to this reality. (For a good "pop" version of what I mean, watch the Robin Williams movie "What Dreams May Come.")