Dear Ana
This is one of the best things that could happen. He has a chance now to detox, get treatment and to learn how to live. I would have gotten the lawyer, too.
I think it’s fine to keep your distance. He will “man-up” and do his time by himself. He got himself there. He can deal with it. Letters are just fine. I would be careful about sending canteen because there are drugs in jail and canteen items or money in his books can get him in trouble, if he’s vulnerable.
I think the very best thing you can do is post here and reply to the posts of others. I’m on a cell so I have to cut it short but I will end this way: You will get through this. This is not on you. It’s on him. And dealing with this is how he will learn and grow. Welcome.
Ps I know how this hurts. You will get through this. Please dont blame yourself.