Can you get hibiscrub from the pharmacy and carefully disinfect the area with a cotton bud, ideally by gently working off the scab? If possible, see whether the bite has fully penetrated the lips. You have to have too keep a careful eye on the lip in the next week or two, in case it develops an abscess.
See how the girls are with each other and if necessary, separate. Sows can fall out and will usually not go back together if they had a fight. It is just a lot rarer than with boys. You can get away with it, if it is just a bad scratch, but once you get into bites, you've usually had it.
I am very sorry that it has happened at such an inconvenient time for you.