What is the expiation for suicide, and is repentance permissible before committing it, or is it permissible to burden the family with seeking forgiveness after death?

Killing oneself is one of the gravest and most destructive sins. Allah has threatened severe punishment in this world and the Hereafter for those who kill themselves. The Prophet, peace and blessings be upon him, said: "Among those who were before you, there was a man who had a wound, and he became impatient. So, he took a knife and cut his hand with it. The blood did not stop flowing until he died. Allah the Almighty said: 'My servant hastened to take his own life, so I have forbidden Paradise for him.'" And Abu Hurairah narrated that the Messenger of Allah, peace and blessings be upon him, said: "Whoever kills himself with a piece of iron, his iron will be in his hand, and he will stab himself with it in his stomach in the Hellfire, abiding therein eternally. And whoever kills himself by drinking poison, his poison will be in his hand, and he will sip it in the Hellfire, abiding therein eternally. And whoever throws himself down from a mountain and kills himself, he will be throwing himself down in the Hellfire, abiding therein eternally."

Patience in the face of trials and calamities earns a servant reward and recompense from Allah the Almighty. A person's sins are the cause of their misery and the calamities that befall them, as Allah the Almighty said: (And whatever calamity befalls you, it is because of what your hands have earned, and He pardons much.) [Ash-Shura: 30]. Repentance for a sin only occurs after it has been committed. Therefore, one must repent from the intention to kill oneself. If one proceeds to kill oneself, they have closed the door of repentance upon themselves, and their end will be evil. This matter is indeed very serious. So, let the servant repent to their Lord with sincere repentance, strive in obedience to Him, and ask Allah for a good end.