He is now nineteen and considered an adult. You have offered help in every form that you are capable of. If he cannot make the first step toward getting healthy, there isn’t much that can be done. I understand mental illness is playing a part in this, but there’s really very little a friend in a different country can do beyond offering emotional support. If there is no one else in his life he can turn to for support, consider looking into his local social services and any other local charitable organizations. What about extended family like an uncle or cousin? A high school friend? A high school teacher? They might be able to reach out and offer some guidance to him.

The situation you’ve been cornered into isn’t sustainable. You need space to live your life, to be healthy, to be happy.

Suggest the aforementioned options, then create some boundaries with him. Tell him he needs to reach out for help locally, and while you are his friend, you are not, cannot, and will not be his primary caregiver.

Boundaries are tough to establish, but well worth it.