If she is eating crow and making inroads towards trying to be a good neighbor, then do yourself a huge favor and try to get along with her. A box of sani-wipes for and a good educational lecture on bio-security can help you save your sanity, and make her your allie. Don't alienate her, I live surrounded by horrible neighbors that do not speak to each other except through law enforcement, and most would not lift a finger to help the other, even in a case of life and death. It is miserable to live this way, and when I lived near a low income housing project in Texas, the people were kinder and more friendly than they are in this wealthy neighborhood in Flagstaff.
Make sure your homeowners insurance covers any potential liability, and try and develop a good relationship with her. She is young, and as such, she may have not had much in the way of home raising and education on how to be a good neighbor, so you have a golden opportunity to teach her how to be one. I wish I had young neighbors that I could teach how to be nice people, but I am stuck with rejects from the "Me" generation that seem bent on making life hard for those around them. Good luck!