I’m very, very sorry for your loss. Like any parent who has lost a spouse, you are having to deal with your own grief as well as your sons’. It’s very hard. I hope you are finding quiet moments for yourself in the midst of your concern for the boys.
There is no good time to lose a mother but the preteen and early teen years may be the hardest. Just when he was starting to do the normal pulling away from his mom, his mom pulled as far away as a person can go. He feels betrayed and angry. To his way of thinking, she’s supposed to be there for him to come back to. He may be feeling guilty for all the very normal times he pushed her away. He’s probably asking “why?” Underneath all the anger, he is probably feeling very sad and lost and vulnerable all the things that an emerging teen doesn’t want to feel. So he acts up instead. If that weren’t enough, his role model for how a teenaged boy handles grief is his big brother who wasn’t able to handle it either.
Ironically, the older son may be your best resource. If he has come out of his drug period and matured, he may be able to help his little brother by sharing what he learned and how he wished he handled it differently. It’s worth a try.
I web-searched “grief counseling, your city and state” and found quite a few support groups, workshops, and family therapists who specialize in helping parents and teens work through grief. Friends and family can love you. Teachers can do their best to give your son some slack. A counselor who has been through this with many, many families can add some practical advice for reaching the boy. If he won’t go, go yourself. It’s important to respond to him now, before he has transformed himself into such a “bad boy” that it’s a huge struggle to find his way out again.
I wish you well.