What should I do about my poor memory and forgetfulness in prayer and Qur'an recitation, given my past suicide attempts?

Suicide is forbidden under any circumstances, as it is one of the major sins. The inability to memorize or perform prayers as required is a trial that requires patience, and Islam is built upon ease. Reciting Al-Fatihah in prayer is obligatory because it is a pillar, and whoever cannot memorize it has alternatives: praying behind an Imam, or saying "Subhan Allah, wal-hamdulillah, wa la ilaha illa Allah, wa Allahu Akbar, wa la hawla wa la quwwata illa billah" (Glory be to Allah, and praise be to Allah, and there is no god but Allah, and Allah is the Greatest, and there is no might or power except with Allah) instead of it, or repeating what one knows well from that, or standing for a duration equivalent to reciting Al-Fatihah. One should also regularly perform adhkar (remembrance of Allah).