Trouble staying alive during gushing wounds as an unholy dk

[Unholynips 0]

Hello I'm a 638 ilvl Unholy DK. During my guilds progression tonight I was taking very heavy damage at 3 stacks of gushing wounds and almost instantly died at 4 stacks. I was using icebound fortitude when the third stack was applied and using my death pact and healthstone when I dropped dangerously low. I dropped anti-magic zone for purgatory so healers could save me when I was going to die.

 

I was still taking extremely heavy amounts of damage and I was dying way too much. I feel like the raid wiped at least once because I died and the groups became uneven. I'm wondering if anyone has a suggestion as to how I can take less damage from gushing wounds. Below is a link to my armory. I would greatly appreciate any input. 

 

http://us.battle.net/wow/en/character/area-52/Unholynips/simple

 

Edited December 4, 2014 by Unholynips

[Peelyon 416]

How many have you got in each group?  The damage is shared so if you only have 2 in each group for example its going to hurt like crazy

[Storm 426]

We did it with 30 people last night, so I don't know how the gushing wounds scales for smaller sized groups, but with a 30 man raid we had 5 people per group, and then having 2 people leave the group was enough to make him switch and target the other group.

 

3 stacks of gushing wasn't an issue at all with 5 people stacked in a 30 man. The only time we died is when our stats didn't reset one time after his charge phase, and we went up to 6 before it basically 1 shot our group.