How do you forgive yourself for doing everything you needed to do to be sure of a major life change?... you didn't do anything wrong that requires forgiveness of yourself. Perhaps the only thing you need to forgive yourself for is being optimistically hopeful that things would change. But honestly, things did change... you changed. It may not have been what you wanted to have happen, but it's what happened.

Tell the doubt and guilt in your head to be quiet. You've done everything you could and it didn't work. Tell yourself to find happiness. Then find it.