There is no need to apologise, Phoebus, you have done a tremendous amount of good for the community, and I firmly believe that you should do what is best for you as a person. Your health comes first, and always should. You don't owe your work to anyone, you should only ever do something because you want to, and if it is making your condition worse, I fully support dropping it like it's hot! I am sure the community will keep supporting the pack, and even if they don't, I think we can all agree that we would sooner have you healthy than a tileset!
I wish you all the best with managing your condition, and hope you can find successful coping strategies to mitigate the effects of it. I also struggle with diagnosed anxiety, and can understand that this tileset was probably a massive burden to keep updated with performance anxiety about the speed and quality of updates! You should be proud with how well you managed, but don't feel guilty or sorry that you stopped, it is your choice and for your health, and you are no indebted to anyone, the only slavery we support is that of elves!
Maybe you will come back later to it, maybe you won't. I believe we can agree that for now it is good that you leave it for now.