Please. Don't give up on your cat. If there is a slight change in surroundings or routine, that could spark this behavior. My cat uses the playroom hallway whenever she gets mad as a litterbox. Although we get angry, we don't give up. If you yell at her more often or dont pay as much attention to her, she may also be this way. Do not give up on your cat. although you were hurt by this action physically and probably mentally, your cat may have felt threatened or frightened for whatever reason. Let your cat cool off for a bit, and then get back to your normal routine. Giving the cat away will only make you sad, and the next owner may have a surprise. giving the cat away may also spark a new trend and it could get even more mad because of the huge change. Thats my advice.