well i don't know much about catholic, but i do think that suicide is not something that should be allowed ! whatever the religion is !and the fact that they teach that since life begin , one become sinful; isn't a good idea at all, because making sins is part of our nature, that doesn't mean it'ok to be sinful but we should prevent ourselves from that. and that is one thing among others which make some people respectful than others.
Suicide can't and will never be a solution to any problem, moreover it's a crime commited on oneself, because a person wasn't created to punish himself or take it away, that's a sign of losing faith.