Well I for one am glad that you managed to find at least some light for this dark ending. Yes, the fleet has been destroyed but at least there are survivors, we've learned that the enemy is not invincible and we even got to hear from them, however shortly.
I think Erasia planning on stepping down as captain in light of recent events was worrisome. Especially in such an open manner. It's a good thing that her first officer talked her out of it but not sure how this will go over with the crew, knowing they're following a captain who is ready to throw in the towel when things get tough.
Otherwise this was an excellent, terse tale and I'm looking forward to meet these guys again in your other story where the outcome is yet to be determined.