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I will try to best answer your question. You are sister-in-law's behavior is unethical and potentially criminal. You would want to file charges for harassment, stocking and potentially criminal trespass if she ends up on your property. You may also contemplate filing a civil suit for slander if it's oral communications and liable if it's written communications that defame your character in the community. There are methods that you can file a petition to attempt to expunge your hospital admission. This is difficult to do and large part of the difficulty depends upon whether you are voluntarily or involuntarily committed. You will definitely need to obtain copies of your medical records regarding your stay. I would highly advise taking action against your sister in law as her behavior seems to be increasing rather than decreasing in severity.
I hope that this information is helpful and I wish you the best of luck with these difficult circumstances.