Does sin fall upon one who curses Allah unintentionally as a result of intense anger?

As long as what you uttered was a slip of the tongue due to anger, there is no sin upon you. No matter how great the sin, Allah's forgiveness is vaster. "Say, 'O My servants who have transgressed against themselves [by sinning], do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, it is He who is the Forgiving, the Merciful.'" It is not permissible to kill oneself (commit suicide) for any reason whatsoever, as it is among the greatest major sins. Remorse is a sign of goodness that should be utilized for repentance and righteous deeds, not for despair and hopelessness in Allah's mercy, for that is a characteristic of disbelievers and those who have gone astray.