Question about Thorns/Retaliation/Instant Leech

I haven't been able to find a good answer online as to whether thorns damage (and therefore instant leech with thorns leech) applies at the exact same time as a monster hitting you, before, or after. Does anyone know? I asked on the subreddit and was recommended to post here (and got told about recoup for some reason).

Essentially, if I have 3000 life and a hit would deal 3001 damage but I retaliate with thorns and leech a few hundred life do I survive or not? Do I take 3001 damage (die), and then thorns and leech happen, or is my effective 1-shot pool (life + whatever gets leeched instantly) up to 2x my life pool (as you can't instantly leech more than your life pool at once)?

Thanks!

You would die because there is an order to the mechanisms even if they are instant.

Leech applies first in scenarios where you are dishing out damage (so whether normal attacks or with thorns), however, in this scenario of retaliating with thorns, you have to receive damage from the enemy's hit first to proc the thorns + instant leech.

The instant factor only means leech doesn't occur over time, not that it will skip the line in the order of operations.

If it worked the way you are hoping, you could be nearly immortal against large hits with enough leech.