Horse abandonment?! HELP?

Okay I have a major Problem and I need some advice from everyone. I have a 16 year old QH mare that is the most awsome horse ever. I have babied her all her life with me, about 1 months ago I had to move due to my work and I was planning on selling her to a really nice couple but a girlfriend of mine wanted her, so we made a verbal agreement and there were people present that she could have her but she had to keep her in the same or better condition than she was in when I gave her to the girl, otherwise I get her back. Well here it is almost a year later and I moved back to town and went by to see the horse and she is severly thin, alarmingly poor! I was sick, her feet havent been touched nothing! and she is in a pasture with about 8 cows, they dump out feed and walk off and the horse isnt getting any! Anyways I cannot take her back to my place because I no longer have the proper space to keep her, so considering the shape she is in I did a little research and found a rescue and contacted them, they want to come get her this coming Thursday. I still own all the papers on her and the original bill of sale, the only "contract" I had with the girl was verbal but there were witnesses. Now she is claiming I abandoned her and that she has invested money in her and that legally the horse is hers. If you could look at her you would see otherwise , my baby is skin and bone! and that as far as I am concerned is breaking our verbal agreement. I need to know if I am in the legal right to get the horse back and see to her safety and well being?