Therapist sounds like a great idea.
Perhaps it would be best to have a conversation with your A regarding a future reconciliation. You have a map, you require 1 to 2 years of adhered sobriety and a recovery program.
Yes, unfortunately there is always potential for a relapse. My husband relapsed after 10 years sober. Some people, once they sink their teeth into it don't relapse. I do believe its more common than not. Once you see the red flags and know what to look for I think it is helpful, a relapse happens in the brain long before it ever hits the lips. I was uneducated about it when my husband relapsed though there were many, many signs he was headed that direction. Now I do feel that if he started walking that path again I would be able to recognize it. I can' stop him from relapsing, but I can enforce my boundary which is "I am outta here".
Its hard to fathom that you have to always worry at least when he initially got sober I still worried. I worried for a long time. Even a missed phone call for several months would raise my BP a little. As I worked my own recovery that feeling lessened and is no longer a part of my life. I do not worry if he will relapse because I have a plan. I have already made my decision what I will do if he does - and he KNOWS it.