As a mom who adopted five kids, two older ones, I can guarantee you that love will not help a child as damaged as an eight year old who has lived his life with both a dysfunctional, probably drug abusing birthmother and then the uncaring (largely) foster care system. Most kids who are in care that long already are too damaged to really attach to us by the time we get them. There are exceptions, but, sadly, your son does not seem to be one, but...it is certainly not YOUR fault. You gave him the only love and stability he ever had. It is basically everyone else who failed him FROM DAY ONE, especially if bio mom used drugs and drank during her pregnancy. Your son is not going to do any better in his life if you hand him money. If he is sober and motivated to work, he'd at least be flipping burgers. My guess is that he is a big liar and that you can't trust his word that he is sober.
My two children that I adopted who were considerably older than infancy were not able to adjust to family life. One was downright dangerous and sexually abused my two younger children for three years and he scared them so badly that they were too afraid of him to tell us. Yes, I feel guilty. As soon as we found out about that, he was gone forever. I don't miss him. But that's off topic. He was tried by the county and found guilty of First Degree Sexual Assault of a Minor although he himself was only thirteen because my daughter was six years younger than him. CPS took him and he was sent to a residential treatment center for young sexual predators where he admitted he never cared about us or anyone, really, and had no idea why he did the things he did.
The other older child was adopted at age six from another country, an orphanage kid. He was very well behaved, but distant. His brilliance saved his life and now he is over a millionaire and doing really well, married with two kids. But he does not think of us as his family and will not see us. At least I know he is safe and will take care of himself, but my heart was broken by this. I loved him as if I'd given birth to him, as I love all of my children. I did give birth once so I know how it feels. That love for all of my children is as strong as that.
My infant adoptions and m y two year old adopted son (who has autism) really worked out well. I feel blessed every day for all three of those now adult children. They are fantastic people. I truly don't believe it is possible, in most cases, to adopt a child from the system who has already lived his formative years in a form of hell and does not trust anyone in the world...and get a well adjusted, loving adult out of that. No matter how much we love them. Much evidence backs this up too.
Whatever you do, do NOT feel any blame.
Your ex-husband didn't help either (sigh).
Do you have a relationship with your son that is mutual friendship, since you are both adults, or does he just hit you up for money? I have a great friendhsip with my three younger adopted kids, a shaky but ongoing relationship with my biological son who has always been a problem, and no relationship at all with the child who abused my other children or with the one who decided we are not his real family.
You are an amazing person. Don't feel bad. Do something great for yourself and start focusing on YOU. Do you have other loved ones around you? That helps. Going to a Twelve Step group or therapy also helps tremendously. You get some balance when non-involved people are able to hear your story a nd weigh in. You in my opinion need to start taking care of yourself first. You are well worth it!!!