I did a lot of mourning the dream when I finally made the decision to leave. It was difficult and I felt like a failure. The good news was that I had a good group of recovery friends who helped me to remember that I was not a failure, the marriage / relationship had failed, and there's a big difference. They also helped me to focus on just what was ahead of me, one day at a time.
What I can tell you today is this: there really is light and life and happiness and healthy relationships on the other side. It just took time, and continuing to work on my own recovery even after I left the relationship. It was the best thing I ever did for myself and for my sons.
It gets better. I promise.