Do you die instantaneously if your life total hits 0?
104.3b If a player’s life total is 0 or less, he or she loses the game the next time a player would    receive priority. (This is a state-based action. See rule 704.)


When the Force of Nature damages you, Spirit Link's trigger goes on the stack. If, between sustaining the damage and getting 8 life back from Link, your life total hits 0, you'll die.

This is confirmed by the Oracle text for Spirit Link:


  You only gain the life when the triggered ability resolves. If you are
  reduced to zero life before the ability resolves, you will lose before
  gaining the life.


Luckily, you can avoid this problem by replacing Spirit Link with Lifelink.