Nothing wrong with protecting yourself as long as it doesn't grow into bitter resentment or just a flip side of trying to manipulate her with warmth. At a certain point you just have to stop trying and let them do what they will. You can be open to working on it, you can even let them know you would be willing to do the hard work if it ever became something she considered in the future, but then you need to get on with your life.
It's like being in a double bind. If you walk away, you confirm to them that you really didn't love them after all and they were right to dump you before you dumped them. If you try to woo them, then you are smothering them. So walk away while making clear that you have always been and remain open to reconsideration and the hard work that goes with that. Neither smothering or abandoning. Just maturity, respect (for her & yourself), and the love to give them what they need to walk their own path. Dropping the rope really is the best thing you can do for everyone involved. You can't love her unless you can love yourself. Loving yourself means drawing boundaries and attending to your needs in this reality, while not abandoning your deep convictions about loving, honoring, and cherishing. In many cases, this means letting go and moving ahead.
Easier said than done.
BTW, as I know you had some interest in Buddhism before, I've like Storms Can't Hurt the Sky: A Buddhist Path Through Divorce by Gabriel Cohen. I've also found Charlotte Kasl's If the Buddha Dated good (she also has If the Buddha Married, but our sitches regardless if it is reconciling w/ our Ws or someone new are closer to the dating book - and she is both a therapist & lay teacher, so this isn't the how to score w/ hot Buddhist chicks in your Yoga class - although there's nothing wrong with that if that's what you're into & its mutual )
Me: 50 W:43 S6, S3 M: 12 yrs. T: 17 M is bad & Not happy Bomb Mar '14 S 5 Feb '15 D Bomb 13 Apr '15 (but "no hurry") DB Coach May '15 Wants proceed on D Aug '15 Starting 1-on-1 negotiations Sept '15