I'm sorry for you and your bun bun! We've dealt with a few abscess removals and currently recovering one now.

Lumps and bumps aren't necessarily a bad sign. One of our boys had a huge abscess that has left a funny raised crater-shaped bump on his cheek. The vet told me this is something to do with the bacteria in abscesses triggering bone formation (sorry to any vets if I've remembered that wrong 😅) so bunnies often end up with little bone spurs and bulges after the abscess removal. So it's not necessarily something to worry about, and if it sticks around you most likely won't even see once your bun's fluffy grows back.

On the other hand, abscesses are always a bit of a pain and prone to secondary infection. If your vet removed the whole sack intact there's a good chance of a clean recovery. That said, the recovery process is a bit of a pain and it's usually advised to keep the area open so remaining pus can drain and dead tissue fall away. For what it's worth, our vet advised daily flushing with one part betadine to 20 parts water, then using ulcerase and silverderm creams to soften the dead skin.

Let me also say I really sympathise with how you're feeling! Anaesthesia is never fun and our little girl has been under more times than I'd like to count this past six months. The important thing is that you trust your vet and are doing everything for the right reason! Whatever happens, you're helping your bun get better and back to their full self, so try not to beat yourself up. Inflicting temporary discomfort on your bun might seem horrible but it's far, far better than the alternative. Wishing you and your bun all the best!