@Kathryn657. A "service animal" is trained, does not require being tied up (guests words) and is never to be left alone. It sounds it was left inside alone for long periods of time. Did you point this out to ABB? Keep to the facts.
Your insights are correct- do not doubt yourself just because you are a new host. It would appear the guests two bad reviews came from the combined family vacation bookings. I note the other guest bad review listing is not showing (and only has one review). All places he has booked on ABNB were with relatively new hosts.
@Fred13 has some wise advice. Do consider closing listing and starting again as the 1 star will weigh against you until (and if) removed.
Its hard but I would have written a much shorter review and left posting it until the 14 days were almost up. Words like ""would not host again" is helpful to other hosts. Assuming you didnt have any incoming guests I would have delayed lodging the claim until then as well. If you're upset then type the longer version of what you are feeling in a word doc separately. After many more hostings you can look back and hopefully be able to laugh about it.
And maybe send that other nice guest a special offer to get them back- sounds more like the type for your listing.