Have you finished fighting her again? Or have you found the blue potions too? This is a bug that someone else also had reported, but according to them, when you finished fighting her for the second time, you should be able to get out of the cave.
It is ok. I get it. Anyway, so maybe the reason I couldn't progress was the lack of potion since I was previously beating her with a over leveled character with no blue potion. Side note just curious how over leveled am I? I'm at level 19. But I'll tell ya how I beat her without the potion. First of all I was over leveled, but I also equipped the orbs I have especially wolf, and start out by attacking her if I don't have enough TP for elven grace. I then would repeat attacking and elven grace with using twin strike on the bandit shadow and bandit hexer since it deals enough to one shot them most of the time at lower levels. Not the mercenary since it takes 3 turns of him either way. I repeat this until the last phase where she has one of each bandit type. There I use meteor surge twice since it is worth it due to hitting 3 enemies. Hexer usually dodges at least one though. I would also use a harpy feather on this phase since it doesn't take a turn and helps mitigate the risk of one of the bandits using the Subdue attack and failing to dodge. (Assuming elven grace and harp feather stack) After that you win. Meteor surge spam doesn't work since I believe it has an increased chance of missing over a regular attack.