I agree with Hoping -- great advice! It's going to be up to you to determine and strengthen the boundaries.

I agree with limiting the phone conversations to a half hour, and also with encouraging him to lean on other supports. He needs to be in therapy. You cannot play his therapist, nor are you responsible for resolving his depression and suicidal feelings. Please take that burden off of yourself, for one, and realize that this is the job of a therapist - not you. He should not be leaning on you so much - that is not fair to you.

Definitely encourage him to seek additional help. You can even tell him directly that while you care for him, you cannot be his therapist. He is responsible for his own self-care and for seeking help, and if he cannot take care of himself or seek help, it is not your job to do it for him. This is something you need to have firm in your own mind.

Wishing you all the best. ((((Hugs))))))