A - Thanks for the question. First off, if you ever serious about harming yourself or know someone who is, then you need to seek help. These kind of thoughts are not normal and you can get help for them. Your life is worth an infinite amount.
Here is a number to Suicide Hotline - 1-800-784-2433. Please use it if you need to. If you are a student at A&M and are in need of professional counseling, please contact Student Counseling Services. If this is a crisis, please call the help line at (979) 845-2700. If you are a student at Blinn, then please contact Center For Student Development at 979-209-7250 for professional counseling.
That being said, here is what the Catechism says about suicide:
2280 Everyone is responsible for his life before God who has given it to him. It is God who remains the sovereign Master of life. We are obliged to accept life gratefully and preserve it for his honor and the salvation of our souls. We are stewards, not owners, of the life God has entrusted to us. It is not ours to dispose of.
2281 Suicide contradicts the natural inclination of the human being to preserve and perpetuate his life. It is gravely contrary to the just love of self. It likewise offends love of neighbor because it unjustly breaks the ties of solidarity with family, nation, and other human societies to which we continue to have obligations. Suicide is contrary to love for the living God.
2282 If suicide is committed with the intention of setting an example, especially to the young, it also takes on the gravity of scandal. Voluntary co-operation in suicide is contrary to the moral law.
Grave psychological disturbances, anguish, or grave fear of hardship, suffering, or torture can diminish the responsibility of the one committing suicide.
2283 We should not despair of the eternal salvation of persons who have taken their own lives. By ways known to him alone, God can provide the opportunity for salutary repentance. The Church prays for persons who have taken their own lives.
In other words, we hope for salvation for those who commit suicide. But, in your final question you ask if it matters whether they were good otherwise. We have to be careful of trying to make salvation a balancing act, where the good outweighs the bad and then we get to heaven. This isn't how salvation works. Our salvation is determined by whether or not our souls are in the state of grace at the moment of death. If so, we go to heaven. If not, we don't go to heaven. God alone answers the question of every individual's salvation based on this criteria.
I have had several friends commit suicide through the years, including one of my good friends from my time at St. Mary's when I was a student. But, he was very sick. As I do with all who have died, I place them in the infinitely merciful hands of our Lord and pray for them.
Peace to you. You will be in our prayers and if you need help, please seek it out.