Talk to him gently and tell him that you care about him but can't be available at all times since you have other matters to tend to. Tell him that if he threatens suicide then you'll have to inform his family. He needs to go for counselling and psychiatrist evaluation. Inform his parents or anyone else who can take care of him.
Next Steps
Since he depends on you emotionally, he might feel lonely without you. Instead of avoiding him, tell him when you'll meet him and talk to him. Encouraging him to make more friends, engaging in meaningful activities will take the pressure off you.
Health Tips
If he threatens suicide, it's an emergency situation and he needs to be taken to the nearest hospital emergency department.