Sounds like you know exactly what to think. He knew all along but was hoping you wouldn't.
IMO, a love letter or an apology letter from an active addict isn't worth the paper it is written on. I had stacks of them. I believed every word of it too. I was naive, stupid, and gullible.
Stay strong, you have come a long way. He knows it too and will try anything to suck you back in. He is running scare, let him!!