Rachel, First off, so very sorry for your anguish. I have been down this very same road twice now, the first time was work related but the second one is more aligned to what you are going through now. Three weeks before Christmas 2012 whilst out present shopping my ex turned to me in the car as we were parking and said to me " I want to be rid of you" by the following April she had packed up what she wanted and left. She was the one who stopped loving me!! not the other way round! I was down, right down where you are now but neighbours kept coming round to make sure I was alright and slowly as the days, weeks and months passed the pain of what I had lost forever started to faid away, I made new friends and rebuilt my life.
Sad as it is, it sounds as though your wife is set on finishing with your marriage, sometimes there is no stopping a person when a decision has been made.
it is difficult for you right now but believe it from me, life will get better and you will make a new and better life for yourself.
Best wishes and PM if you need to talk