I have two friends that I used to work with and coincidentally they had both experienced estrangement from their daughters, under similar circumstances. They had gotten divorced when the daughters were around 12 or 13, and the girls in both situations went to their respective father's home for regular visitiation, and eventually the girls chose to live with their fathers. I'm pretty sure in one case, the father poisoned the daughter against the mother--I can't remember what happened in the other case. I knew both women very well, and liked and respected them very much. They were loving, smart, hard-working, nurturing people. In fact one was an RN and the other a psychologist.
From my outsider POV, I could not understand what they could have done to deserve such pain, and such hatred and anger from their children. One of the friends attended therapy with the daughter while all this was going on, but it didn't help. In fact, the therapist seemed to "side" with the daughter, but of course, I only have my friend's perspective, which was clearly biased.
They lost out on contact with these daughters throughout the girls' growing up. But in both of my friends' cases, once the girls reached adulthood, they reconciled over time and wound up with good, healthy relationships.
I am so sorry for all of you who are going through this.