Generally, once you have been in possession of the premises for 30 or more consecutive days, a landlord-tenant relationship has been created that can only be terminated by a special proceeding in court. In other words, if you lived there for 30 consecutive days or more and your husband's sister evicted you without a court order, the eviction would likely be illegal and she could be held liable. Therefore, you would be well-advised to consult a lawyer to review your options. On the other hand, you should consider the long term consequences of whether you would ultimately want to continue living at that residence before proceeding further.
The above statement is intended for informational purposes only and does not establish an attorney/client relationship.
Dear Buffalo resident:
You are clear that you are not a tenant, as you did not mention that you and your husband pay his sister to live in her house.
New York law requires that a landlord use a special proceeding ( a summary proceeding ) to evict a tenant. Where no landlord and tenant relationship exists, the landlord is allowed to use a shorter form of notice ( a ten day notice to quit) and in case of an unwanted or overstayed guest, the notice to quit is directed to the "licensee" whose license expired. The landlord would the sue in a summary holdover proceeding. Unless the "licensee" could prove a landlord and a tenant relationship, the court would grant a judgment to the landlord (may even allow for a money judgment for the reasonable value of the use and occupancy) and allow for the eviction to be conducted by the appropriate law enforcement department.
If you want to sue for an "illegal" eviction, there is nothing that could prevent you from doing so. But from the "facts" you presented, a jury will have to consider whether you have any damages, and if so, should the damages be more than $1.00.
And if you want your sister-in-law to go to court to evict you, then she probably will do so.
The answer provided to you is in the nature of general information. The general proposition being that you should try to avoid a bad outcome if you can.
It's crazy how people will treat family.
I may be guessing or not licensed in your state. No atty/client relationship exists. I earn my living collecting points for "helpful" answers.