What choices you make regarding the grove have no impact on the artifact
Artifact is a story critical item - it will become part of the story even if you come out of your way to never interact with Shadowheart. I think theoretically it should be with Shadowheart if you have her with you, and if you don't it will magically transfer over to you. The game gets confused - I had shadowheart with me for almost entire playthrough, and at some point the game decided I have the artifact regardless.
