@Thea-and--Keith0 The only thing that to me you did wrong was comp them the weekend. Why did you do that? Comping them the Friday night is all you should have offered in the first place, as they had no heat, especially since you brought over space heaters, wine and flowers.
There was zero need to offer to comp them the weekend, and even the pet fee, when the heat was an easy fix the next morning.
These people are users- they didn't appreciate you trying to make things right, instead taking advantage of the situation by not only getting fully refunded, but leaving you a dirty mess.
I'm not sure what you mean by should you wait to see what they will do? They got fully refunded, and left. What else would they do or feel the need to do?
I have to say I disagree with @M199 as to what to write. S**t happens. Sometimes things break or malfunction. There's no need to apologize to that extent when you bent over backwards to deal with the situation, and I certainly wouldn't say anything about your standards not being up to normal. This has nothing to do with standards. Appliances can go on the blink with no warning.
If they write a bad review, you can always respond to it. Maybe wait to see if they bother to leave a review at all. If not, you could wait until day 13 and a half to leave a review.
My brain isn't up to a suggested review to leave for them at the moment. But it should both acknowledge the heating issue, which you are sorry for, and that you acted to remedy asap and also mention that they left a mess.