Is it legal for my stepmom to throw me away after my father just passed away?

You provide too little information for anyone to give a proper answer. If your left a Will, to whom did he leave hi portion of the house to? How was title to the house held if joint tenancy than she got the entire house. If you were not supposed to pay any rent, it is unclear if she has to give you the same legal notice as with a tenant. You need to go to an attorney who handles such matters to see what can be done. She definitely must give you a reasonable opportunity to get the possessions you own.