Well you made your bed - now give it back to her.
If it was her stuff before you got together, you really are better off handing it back. I understand your viewpoints but at the end of this day this was her property before you got together and probably cannot be considered a joint asset.
She is a woman scorned, so she will use anything she can to get to you. She will be a complete cnut to you but the moment she steps into court or a police station, she will be able to turn on the water works and you'll be fucked. No-one will believe your word against that of a woman in tears.
It's just a bit of furniture at the end of the day.
Arrange to have it delivered to her place. Do not let her come and get it and do not go with the delivery guys that take it to her place.