It happened to me this morning too but I managed to clear today's galwar.. As for healers, there's always Daka from Cantina so maybe you could consider getting her..and like what the other players have mentioned, try having other filler characters to use for the war.
One tactic you could consider is, just use your fillers as pawns to bait your opponents to use their ultis. And if your fillers are still alive after that, retreat from the battle immediately and swap in your alfa squad.
Anyway, I had to deal with the lv60 players up untill the 4-5th battle before clearing up the hoard of AIs after that.
I honestly have no idea how they do the updates and team resets..hope you'll have better luck tomorrow.
