She is most certainly dead. She is not part of the Godhead. She is human. She is not our Savior, Jesus is. We have to be very careful adopting beliefs like purgatory and Mary being somehow tied to our salvation when there is not Biblical support.
1 John 2:1My little children, these things I write to you, so that you may not sin. And if anyone sins, we have an Advocate with the Father, Jesus Christ the righteous. 2And He Himself is the propitiation for our sins, and not for ours only but also for the whole world.