You can, but be aware that the buyer can still have the last word by replying to your reply!
May be best to wait a while until they've moved on and are not looking for your response every day.
We don't know what happened, but be calm and factual. That's another good reason for delaying a bit. Remember that it's to explain your side to your future buyers. So many sellers just make things worse by hurling insults at their buyers!
