There's this old fanfic I used to read on fanfiction.net probably around 2005-2008 and I remember it being good and I want to find it!

I can't remember a ton but the storyline was something along the lines of... somehow Kagome ends up stuck in present day as a demon. She has long white hair, claws, etc. Inu Yasha is stuck in the past with everyone and is human (maybe missing an eye too or something?).

It may have been something like the jewel was complete, Kagome caught Inu Yasha and Kikyo together and Kikyo tries to kill her and Inu Yasha wishes she will survive and so he gives her his demon side?

In present day Sessomaru has survived and he finds her. He has gained wealth and learned how to pass as a human and invites her to live with him. They fall in love etc.

It was super angsty and would go from present day in Kagome's POV to the past following Inu Yasha and Sessomaru showing what happened after she left.

It maybe this is the story your looking for.

Kagome's Blue Light by: Earthnfarie
Rated: MA
www.fanfiction.net/s/4736246/1/Kagome-s-Blue-Light

I know that there is other out there. But I can’t remember off the top of my head. Hopefully this is the one.

Close but no! Unfortunately in the one i'm looking for everyone is dead in the future save for Kagome and Sess

I believe you are looking for : Its rated MA NO YIMS PLEASE ! This story has been remade so if will probably vary from what you remember . Also found on fanfiction; has 23 chapters on both sites, not complete
To Wash It All Away by Crystal Echoes
www.dokuga.com/fanfiction/story/6571/1

I would have been spared the pain, but I would have missed the dance. A dedication for those who have loved and lost. (A remake of the original which will not be reposted. Rated MA because here I won't hold back my writing and if you want a M version its on ff.net)