Forum:The end of the Normandy

Sorry if this has been asked before, but can someone please explain to me what happened to the Normandy at the end, or to be more precise, why???

What was the Normandy doing in FTL? Where where they going? Why would they leave Earth in the middle of fighting the Reapers? Why were all my squadmates on board when just before my last mission they were fighting beside me on Earth, and how did they get back to the Normandy in the first place?

Any answer will do, speculate away. I don't really expect anyone to actually know for sure.