Mainly, what did you think about the revelation that the humans and Teventer did not destroy the elves, but instead the elves destroyed one another and that the facial markings were actually slave markings?
I interpreted Abelas's statement as implying that the elves weakened themselves through infighting which led to their downfall at the hands of Tevinter. It reminded me somewhat of Gildas's account of the collapse of post-Roman Britain - he blames moral depravity and infighting amongst the Romano-British kings as the reason for their downfall at the hands of Pictish, Germanic and Gaelic tribes.
So in short, my character still blamed Tevinter but acknowledged the need for unity amongst contemporary elven populations to ensure that the same thing wouldn't happen again should an elven nation be reconstructed. Regarding the facial markings, it didn't bother my character as they have acquired new meaning amongst the Dalish who are egalitarian - why worry about what a long dead group of people think about your face tattoos?
I think the concept that the blood marking being widely revealed to be slave markings and that elven society in fact wasn't much different from Tevinter would likely similar to what happened to the Aiel when rand revealed their past to them. It will make them either stronger or break them and some of the dalish might still break from the revelation even if the society as a whole doesn't break, not to mention how it might affect their already complex relations with the city elves.
I don't see why it could 'break' the Dalish - regardless of what some people say about them they are a flexible, adaptive and self-critical group who, although believing themselves the heirs of elven culture, acknowledge how much they've lost. This codex entry from DA:O on Aravels even implies that the Dalish already know a little about the social stratification intrinsic to ancient elven society, and this particular elf abhors it:
The keeper says that one day the Dalish will find a home that we can call our own. But why? Why should we tie ourselves to stone constructions like the humans and the dwarves? What is wrong with the life we have now? We owe nothing to anyone, we have no master but ourselves, and we go where the halla and the gods take us. There is nothing more wonderful than sitting on an aravel as it flies through the forest, pulled by our halla. We are truly free, for the first time in our people's history. Why should we change this?
--From the journal of Taniel, clan hunter.
Regardless, despite its large flaws, Ancient Elven society sounds a lot better and a lot more wondrous than the Tevinter Imperium which seems to have been far more blind and ignorant in its [mis]use of magic.