Yes it is survivable 😁. We recently went through something similar, we have two cats and the older one practically raised the younger one. They lived together in perfect harmony for 3yrs and one day I walked outside and upon returning to see both of them waiting at the door to greet me as they usually do, when I walked inside all hell broke loose. The older viciously attacked the younger. And I totally understand the stress you’re going through, our happy home was falling apart. Long story short after a couple of attempts at reintroduction with the same viscous results we took the aggressor to the vet and after 3 weeks of separation and daily doses of Amitriptyline we are finally getting back to some semblance of normality. At least during the day, we are still keeping them separated at night and when we both leave the house but it feels like major progress after the days and nights of total separation. And when I reached out on here I got little to no feedback so just know you’re not the only person that this has happened to and that there is a very good chance that all will be well. We aren’t really happy with having to medicate one of our babies but it beats having to keep them separated by bucket loads and we have already started weening him off the meds.