No two rabbits are bonded until they’re both fixed and have gone through the bonding process. What you had were two young rabbits that got along because they were young and hormones were not coming into play.
They should not be together at all actually. It’s good you knew to neuter them, but from pre-neuter to 1-month post-neuter, they should not be together at all, to prevent these kinds of things from happening. They have bad air between them that they need to forget and repair, so they should be completely separated until the neuter areas are healed, in addition to another month so hormones regulate to normal.
For the first aid, I’d recommend going to the vet for a professional assessment due to the affected area and considering the operation itself.
Separate them immediately. No play dates. At all.
The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.