I have contemplated it twice in my life, and every time I got myself through it. I though on what effects it will have on my immediate family and I realised that I love the few people I have in my life to much to put them through it. 2 years ago I met a young woman in her mid 30's 2 months after her husband committed suicide and I saw firsthand what suicide can do to the people around you, even the ones that you think it won't affect, it affects everybody you know. She found him hanging in the garage, he left no explanation. I almost destroyed her; she sat with all the debt since life insurance etc. does not pay out in the case of a suicide. She had to sell their home and their business to cover the debt.
It didn't only affect her and his parents but also his parents in law and her godson who looked up to him as his father even if he didn't live with them. Even now after 2 years when she talk about him there is tears in her eyes, it affected her and everybody's lives around them. She tried a relationship a while ago but when the new guy decided it was too much work he dumped her and now she has even more doubt thinking she is being punished for some reason because she lost 2 men in her life the last 2 years.
Another friend of mine committed suicide 5 months ago, he thought nobody cared about him, the day of his funeral more than 60 people showed up, people flew up from everywhere around the country that have met him online etc to pay their respect. All I can say is really think about what you are about to do, not just to yourself but everybody that have met you in your life, are around you every day and even the ones you think don't care about you.