I don't think it's any of their business necessarily, even your husband.  I'm sorry if that sounds harsh, but you have to take care of yourself.  You don't owe anyone an explanation, especially if they are critical of your decisions.  They need to learn to respect those boundaries.  You don't have to compare yourself to your nephew because your entire reality is framed in a different context.  You don't have to answer for your AS or the treatments, and you wouldn't have to answer even if you did drive to shady parts of town and spend thousands of dollars.

I don't mean to be cryptic but why do you need to explain anything to anybody? You have AS and that alone should be enough for anyone. If they are truly concerned about your health then there is lots of information on the internet that will explain your pain and all the issues you are dealing with with AS.

Okay, so here's a bit o' drama for you. My sister and mom have "suspected" me as an addict for 5 years. I have some family history with a drug addicted brother and cousin. I have always followed the straight and narrow path, but understood where they were coming from, so I was very open and honest about my pain management to help with their fears.  It turns out that was the wrong thing to do, as some money had turned up missing at my mom's home, so she blamed me. That among other reasons....I've finally distanced myself from them. I'm really happy about my decision. I'm grateful for a husband who is supportive of my pain management. I do feel like it is his business, however. And building a relationship of trust with your spouse does take a great amount of faith from both partners. Nurture and validate his concerns. But don't give into any guilt trips. As a show of good faith, together, you could both look at a 12 step recovery book, or class and openly and lovingly address each others concerns. Pray and/or commit to each other together, out loud each night. He loves you. He's afraid you're going to die. Show him compassion and a spirit of love, and he will only do the same for you. ((Hugs)) Good luck!!