I understand exactly how you feel. My XABF seemed to forget me as soon as I left our home. No texts or calls.....absolutely nothing. His family the same, this was after 5 and a half years together and his mum calling me her daughter in law most of the time although we were not married- we were all so close and then in the blink of an eye. Nothing.
It makes you feel so insignificant I know. But I also know what you have set out very clearly in your post, it is for the best.
Addiction is a family disease. I have recently learnt this and finally see exactly what is meant by that. Understandably he will be their main concern. I tell myself God knows what mayhem they are dealing with all the while I'm wondering why everyone forgot about me. Either that or the power of denial has them all in some false sense of "oh everything will be fine now he has realised this wasn't the relationship for him". I'm not sure which is worse.
It does get better. You are only a couple of weeks along. Just wanted you to know you are not alone in feeling the way you do. I'm sure you know by now how similar our stories are and what addiction does to love. Take care.