Drop it and let it go. There is no hope, dude.
She said that you need to be engaged to work things out? This is definately not love, but infatuation. People who are infatuated with each other feel that they need to get married, right away, to stay together. You get the picture...
She didn't demote you to 'dogwalker'. You've demoted yourself to to that status. Don't walk her dog! Let this bitch walk her own dog!
I know that you are hurting and that's OK. Let your emotions out, in private, but don't do it in front of her. Never let her know that you are hurting.
Take her advice; date other women, move on and forget her. There is someone out there for you that won't be tempted to kiss their ex, when he is back in town!
~V