I was a bit scared when I started to read the story because of the tag combined with realistic set-up, but at the end I happy to have read it. I would prefer if you could let her live so I can read the rest of the story. The idea of ripping of her breasts could be fun, that could happen by accident and the two could use the pins they have to try to fix them. They would attache the piece of her breasts together and then back to her body and hop it heal well.
It could be also practical if Tatjana discovered by luck on her an acupuncture point that suppress the pain. So she could use a needle for this instead of a drug.
Maybe in addition of only needle the couple could also use some string to do recreational suturing. It may even have practical purpose : http://g.e-hentai.org/s/967c33b55d/69352-16
I have a last idea but its in my opinion the most random, after stretching enough a perforation (in breasts or belly for example), Sai could put an onahole inside it so he can fuck it “safely”.