Ok - deep breath - I had a violent Ex. I dreaded my daughter one day suffering at his hands, but I did let her go to him every weekend as he had never harmed her. It was so hard, I was so worried. Yes I knew he loved her and she loved him. Then he took her to Greece one year (three years after our separation) when she was 13 and she left her purse on the table of a bar that he had refused to leave until about 2am, he was very drunk (an alcoholic). She said that he had pinned her up against a wall by her throat (very Nigella) and she had been so afraid, stuck there in a country with no-one to turn to apart from his girlfriend, who resented her being with them anyway. She steered as clear of him as she could for the remaining two days, burst into our house when he brought her back without saying goodbye and I could tell from the way he slunk off that he had done something that he was ashamed of.
I reminded him that now she was 13, he couldn't force her to see him, it was up to her. She made excuses not to see him for a few weeks, gradually seeing him again but not quite as often. I let her call all the shots, despite him being a real pain in the neck and saying I should make her see him. I just felt, he is her real father, I don't want her blaming me in latter years for not staying in contact. So when my now husband and I decided that we had had enough of living close to him purely to enable her to see him easily, we gave her the choice to stay with him or come with us. She had so many friends in the area, and other family, that I think we were all surprised when she chose us. He kidnapped her for a few days, blaming me. It was entirely her own choice.
I put myself through all that for her, He was awful when he came round, frequenntly didn't bring her back when he should have done, sometimes days late, was abusive and a stalker and I would never put myself through that again, ever.
I only discovered years later that when my daughter wanted to tell him something that she knew he wouldn't like, she said that it was my idea. Not everything is as clearcut as it appears on the surface, but of course i would be devastated if it were to happen to my own gentle caring son. But maybe he too could turn into an alcoholic one day and hide it from me.