I feel the same way - I experience(d) shame and guilt at my son's behavior. Horrified, was another word to describe my feelings when I found out some of the illegal stuff he was doing.
The first time he went to Rehab at age 16, I confided to co-workers believing they would understand. It was my first experience and I wasn't sure how to handle it. I noticed I was treated differently by two of them.Not all people understand and this caused more hurt.
I didn't tell a soul when my child ended up in prison years later besides my closest friend whom I've had since I was a little kid. Her reaction was not to say , "I'm sorry that is happening to you" but to then tell me how incredibly well her son was doing. She went on and on and didn't stop about how well she raised him and therefore he was such a success today. I was incredibly hurt by her response and was unable to maintain my friendship with her after that. I realized she too judged me despite that I raised my other child reasonably well. I had in the past shared in her son's success but for her respond to me in that way hurt my soul.
Now, I'm more guarded as to who I trust to confide in with no judgements coming from them. Instead a listening ear and a shoulder to cry on. Ironically, I found two others at work whom have similar stories involving their children which I wouldn't have known about had I not shared. Still, I would warn you to be very careful as to who you share your story with. This is a safe place with those who have walked in your shoes, understand , and can provide you with solace. I'm glad you are with us.