What your therapist said makes a lot of sense. If visiting them in the past has often gone poorly, it's difficult to imagine this time being any different, especially if you stay with them.

Obviously I don't know your financial situation or if there would even be a place open on such short notice, but I think if you could swing it an AirBnB/HomeAway could be a happy medium solution of sorts with your therapist and it would be a buffer between you and your parents in case things go poorly.