I'm sorry Florence, that is so very sad for your son
Can you find some consolation that it sounds like he won't have to totally lose his other family since his stepmom is still interested in keeping a good relationship with him for the sake of his brothers? It doesn't sound like she is going to do quite the same things your AH did. So things are all change for him again, but he does seem to be able to talk to you about how he feeling and that is very important and valuable and you should be proud that he thinks enough of you as a Mom to feel comfortable to do that. Don't beat yourself up about these people being in his life, we do the best we can with what we know at the time, when we know better we do better, right? And it sounds like you are doing an awful lot better. (((hugs)))