Oh, Tammy. I feel so bad. And you have NOT failed!!! You are one of the best, most conscientious dog owners i know! Whatever happens, it is NOT your fault!!!
I wouldn't let my husband bully me into not attending to my animal's needs, but I also know that's hard to do. (like Evelyn, I've had a lot more years to practice standing up for myself!

). And the timing COULDN'T be worse, but that tends to be the case with these things, whether it's kids or animals. I've spent holidays in cold barns with colicking horses and mares having trouble foaling.
That said, I DON'T think Tillies's problem is acute, and it's going to take some time to sort out. Could you call your regular vet, explain the symptoms (just like last time) and ask if, under the circumstances, you could pick up another round of antibiotics (or whatever she was on before) to get her started on.
Then, after Christmas, I'd see if I could find a good holistic vet in the area, who can look at the WHOLE picture. If that person is experienced with Havanese, so much the better. I'd also ask that vet if they have a trainer they could recommend who cna also look at the whole situation and help figure it out.
The problem is that whether the root cause is physical or behavioral, there are serious behavioral aspects to it at the moment. And sometimes things that start out as physical problems can become ingrained behaioral problems unless they are approached from both angles. Certainly, I wouldn't let her NEAR the bedrooms without close supervision for a long, LONG time at this point. (I'm talking months to a year, here... You've really got to TOTALLY prevent that behavior, and let her start building positive experiences again.
Another resource that I haven't heard you mention is Tillie's breeder. Have you contacted her? Breeders know the dogs in their lines. She might know of another dog that developed similar problems, or be able to give you some insight into how best to approach the problem.
In any case, you ar NOT a bad person, and Tillie is NOT a bad dog. You need to remind DH that Tillie is a member of the family, and her needs have to be considered too. Just as it is expensive to buy a nice dog, there are also expenses (often completely unforeseen) that can come up once you have an animal. He needs to understand that, and at least not get in your way when you are trying so hard to figure out a solution.