Is commiting suicide thought of as a sin in the Lutheren church? or would I be forgiven if I prayed before I commited the act?

Life is too short, and risking it on a belief in an "After Life" is just silly.

Get help from a Good Councilor and live THIS LIFE to it's fullest.

It's good that you realize that dying (no matter how) may have some consequences for the next life.

The problem with suicide is that God is really only the appropriate one to decide when we should die (unless there is clear evidence to the contrary---such as "Greater love no man have than this, that he lay down his life for his friend).

So really, this is between you and God.

But, at a minimum, I think God would want you to everything you can to understand why you think this is a good idea and perhaps reevaluate your position on the matter.

And that would require, at a minimum, counseling.

Personally, I think you have value just because you exist, and I can guarantee that you will be missed because you also offer much to others even if you don't really think either is true.

"Any man's death diminishes me, because I am involved in mankind..."  John Donne, Meditation XVII - Meditation 17

(John Donne was one of the metaphysical poets.)

This is not Lutheran inspired, but life is hope, and giving up life is giving up hope. Keep the flickering candle going, for even a flickering candle can start [inspire] a great fire.