You are not being paranoid: he is having a relapse. In this times, nothing you can do for him, but everything you can do for yourself: keep distance from him (live somewhere else); if you want, text him and say that you will be ready for a chat about the situation once he’s sober; talk to your friends and family about how you feel – if necessary, speak to a professional (GP/Counsellor/ Therapist…).
Once he is out of relapse – which could take anything between a week to several weeks – encourage him to talk about what the trigger was and to also book an appointment with his GP to discuss about it and maybe get onto antidepressants. If he refuses, you need to consider that this probably happen again soon with all the urges and the brain alterations he went through.
Stay strong and think of your well-being first as it is crucial if you want to avoid being damaged by this.
Courage!!