Good tips by the previous posters. It took me almost a dozen tries to finally beat the mission.
I loathed this mission. It felt overly difficult, even with healer companion. The sudden difficulty spike is not challenging in a fun way. I was frustrated and it made me, as a player, stop caring about continuing the story. The mission feels better suited for a Flashpoint rather then a story mission. I'd rather Daily and Flashpoint grind my characters to level 55 then play the mission ever again.