Find a good bully vet who does C-sections, as bullies should not whelp their pups naturally. That is a good way to loose mom and pups. Then get ready for several weeks of sleepless nights, as you can not leave pups in with mom all the time. She may accidentally crush one. Keep them warm, as in 85 deg. F. warm. Then a few months after she has the pups, I would get her spayed, so this will not happen again. When they are in heat, you can not let her out od your sight for one second, as you have found out.
I like the part, "wasn't supposed to happen" like humans eh? Everyone will be fine....breathe....and make the best of it. You got a few breeders in here and great info on EBN but like mentioned, specialized bully vet is #1 for you right now. Heh, It is what it is so just enjoy it.