I'm Catholic, and my church used to teach that people who committed suicide were denied Heaven. However, we've become more tolerant of some things over the past 30 years or so, and now there is an understanding that suicide is an act of desperation, and that the person is not in full control of his/her faculties at the time. Therefore, he or she can be forgiven and enter Heaven, presumably after doing some time in Purgatory where people who are not in a state of grace go after death.

Even if you're not Catholic, however, I believe there is forgiveness and mercy. God knows our hearts, and He knows when we've reached the end of our rope and can no longer hold on. He understands. Man often does not.