Can a friend sue without any signed lease or agreement? She is angry because I decided it would be best that she not move in because she had a man who is bashing and making threats on Facebook. I told her she should report this to Facebook and she won't. I came to the realization that he could follow her to my home and potentially put me and my home at risk. Prior to this, several years ago, she was married to a man who after investigating, we realized that he was involved in the burglary of my home. I reported this to the police and while they tried to tie it together were unable to. He had also stolen from her as well during their 6 month marriage. The investigator she hired found he had many marriages, not just a couple, clearly there was a pattern of him being a con artist. Her judgment is questionable and while we had talked of her moving in with me, I realized that this would not be a safe thing for me considering repeated bad choices on her part. She had started bringing artwork and a few items to my home when she was coming to Houston for other reasons, a death in the family and to work for a customer. She is angry that I wrote her a letter that I was sorry and explained that I simply didn't think it would work out because of this other relationship gone bad and because he was bashing her and making threats, that I felt this would put me at risk of drama following her to Houston at my home. Now she is doing to same, endlessly bashing me on text, and also blaming me for all that has gone wrong in her life. She has provoked others in the past and is trying to provoke me. I am standing my ground, not responding to her texts except to ask when she might be picking up her things she left here. She wants me to compensate her for her trips back and forth while she was in town for other reasons and just thought she would start bringing her things. I do not feel that she has any right to ask this of me as it was her doing. She has shown herself in the past to be vindictive in her relationships if she does not get her way. She also wants to sue for me not wanting to be available to take care of her several years ago when she wanted to come to Houston for a mini-facelift. I simply was not in agreement, knowlng full well that she did not have the money and was going to finance this procedure. I told her I was not going to be available for her. I know it sounds crazy and it all is to me. I am ending this relationship once and for all. I feel I have every right to do what I have to protect myself and my home from any more potential risk.

What really matters is what you had in writing. An oral agreement doesn't hold water in tenant relationships - except that you allowed her to drop things off, and small claims judges can be arbitrary at times. She might provide emails or texts that you wrote, agreeing to her move in with you? That counts for something.
The man is what I would worry about, if she decides to join forces with him for some crazy reason against you. Stranger alliances have happened. If you live alone consider getting another roommate.
Personally I would contact her, arrange an hour at your place to get her things, and tell her beforehand that you want to clear the air over lunch and not part bitter enemies. But only you know how far the arrangement got and how far apart you are now.

There are Statutes of LImitations in every State. How far back she can reach to bring up old problems varies by State.

In NY oral agreements do matter - if they make sense. If she planned to move in with you, with you consent, to the extent that she belongings in, made plans, perhaps gave up wherever she had been living and you changed your mind I believe she would have a case against you. How much did the moving in/not moving in fiasco cost her? That's all that matters.

Unless your reasons for cancelling became known to you after you made the moving in/moving "stuff" arrangements were made I believe a Court could decide that you knew the circumstances, agreed to the arrangement, changed your mind, cost her time and money.

On the other hand - is she really going to sue you? Only you know.

I'd stay far, far away from her.

If you had agreed to let her move in, and she started bringing things in, she acted upon a offer you had already made. So if you decide not to let her move in, she can sue for the costs or value of what she had done in preparing for the move.