I have gone through hell and back. Something changed in me after a recent call I received on Christmas Eve. I started fighting for me, not worrying about my her or what she was really saying. Thanks to the hyper analysts on this (like me), I could see the game and hooks VERY clearly. I kinda floated above the conversation and used it to heal. I asked questions that I knew would lead to my healing. I never want her in my life again and all the associative hell.
My boundary pivotal point was hearing that she had slept with the other guy. Right or wrong, I had to make her now "tainted" and untouchable. I believe what helps is to CONVINCE your mind of a boundary you know they will cross and put all the justification of breaking up with them on that. The wiggle room and deniability she masters always was a challenge with my logic. I would even come up with reasons to get out... .yep, I was in deep. But once I heard straight from her she made the choice to sleep with him THEN to hear her on the phone telling me "her heart belongs to me and I love you, miss you... ." yeah, that heart didn't stop you from sleeping with him.
Christmas day was the best for me. The perfect gift of being able to remove her from my mind. I no longer look at her the same... .almost sad, but hell whatever works, right? For you that still suffer, try to build a boundary you know they will break and use it SO YOU CAN break with them on your own terms. Don't look back, stalk, project... .
Hope this may help... .It certainly did for me
