Patricia,
Terminating an employee is never a pleasant task but becomes the responsibility of those in a supervisory position. I commend you on the steps you took. Even though it was within the probationary period, you still took steps to help that individual improve her performance and you kept documentation regarding your conversations and expectations. I also like the fact that you had someone else in the room with you when you actually did the termination. That is just a good precautionary procedure should there ever be a lawsuit or dispute regarding what was said or done. Your calm demeanor also goes a long ways in assuring that the employee understands what is happening and what her rights and obligations are going forward. Good job!
Pat