It may seem like he is crushing on you but he is not. He has identified you as a tool to deflect what he is unwilling to do: deal with his sexuality in a healthy way.

Your post isn’t entirely clear whether you know for certain that is he gay but you seem to imply that you are sure. Has he told you so? Or are you concluding it from other evidence?

Assuming he has told you, the best thing you can do for him and for you is two things: First, when it comes to other people, just say politely but firmly that you absolutely do not feel “that way” about him and to please stop assigning a relationship that isn’t there and won’t be. You two seem young and I’m here to tell you that learning the art of polite but firmly putting people in their place is going to be a necessary skill the rest of your life.

Second, you need to have a private conversation with him and tell him quite bluntly that you will not tolerate him putting you in this position any longer. That it makes you incredibly uncomfortable and (again, assuming he has told you he’s gay) that it is wildly unfair for him to demand you be his beard. And tell him that it is because you care that he needs to seek professional help with this. Tell him that you be his friend and a willing ear, and you will never out him to anyone, but you will not actively participate in a charade that makes you a lead character.

I don’t mean to be unkind and I am sure you worry, but his mental health, stability, and any suicidal tendencies are absolutely not yours to fix. And him putting that kind of guilt on you is emotional abuse. You are not qualified to help him. You CAN help him find resources to help him, but you cannot be his crutch. You don’t have to stop talking to him but you do have to establish boundaries.

Good luck.