When the game first came out this quest always crashed for me when trying to transition from Talos temple to Cidhna mine, however since the latest patch I have done this questline both ways on different characters (once helping Forsworn, once killing them) and it has worked fine. The only thing is I tend to end up with some corpses that never despawn from Markath.

It's not you - I just find it humorous how many people seemingly don't read any posts and just answer based on the OP or the title.