You know, you did have those 89 days. So yeah, "officially" you're back on day one, but not on square one. You have the experience of 89 days now.
Maybe sobriety is progressive, just like alcoholism is a progressive disease. The more you do it, the more you gain the ability to stay sober.
So it's back to being sober. Just like you were. This is just a small setback.