It is perfectly normal to feel the way that you did after receiving that email. Like a punch to the gut. It is something that I have experienced myself.
Is there hope for your M? Only time will tell, because nobody knows for sure. Personally, I used emails/convos like the one you received as motivation. Perhaps it wasn't healthy, but one of my goals was to improve so much, that my W would regret her decision. Eventually that wore off, but it served its purpose.
This email doesn't define you or what you need to do to overcome this. Your journey is independent of your W's journey. The future is unknown, so keep doing what is within your control. You be the author of your book buddy. I believe that you will choose to make it good.
Remember, slow is fast and fast is slow?
Me:45 ExW:48 M:04/97 3 Bombs & 2 ReCons 1st BD 11/10 D Finalized 4/20 D-16 S-14 Going in one more round when you don't think you can. That's what makes all the difference in life.~Rocky Balboa