Is it possible for a man to marry a woman he loved who passed away, so that she may be his only wife in Paradise, and must he refrain from marrying in this world to achieve that?

The mercy of Allah is vast, and it is not difficult for Him to make the girl your wife in Paradise. Be keen on performing the deeds of the people of Paradise and living upon faith and obedience to the Most Merciful. You must also hasten to repent from your suicide attempt, and thank Allah for keeping you alive, for the consequences of a suicide attempt are dire. You should not shun marriage, for it contains great good and many benefits, and your marriage to another woman does not prevent that girl from being your wife in Paradise. Beware lest your love for a woman turns into infatuation, for it may lead its owner to undesirable consequences, and it may reach the point of disbelief, and your marriage to the one you love may be evil for you.