Dark Souls Remastered | Defeating the Golden Crystal Golem (second step to starting DLC)

The first step is defeating the Hydra in Darkroot Basin, but that area is not accessible until you first defeat the Moonlight Butterfly and acquire the Watchtower Basement Key.

Once the Golden Crystal Golem is defeated, Dusk of Oolacile appears. I accepted her invitation to pass on knowledge to me, but I accidentally killed her afterward. I've never done that before, so I don't know if it's going to affect anything. She provided 1000 souls and no loot (this is on NG). I was still able to progress through the storyline and start the DLC.

Getting to and defeating the Hydra:

https://youtu.be/2jjPjmI4rPI

Defeating the Moonlight Butterfly:

https://youtu.be/eEF7KF672dw