I have only read the OP. I am very sorry to hear about this and in general about how hard your life has been - single, with an autistic child still in diapers, and now this.

I must tell you, however unpleasant it would be for you to hear that, that your OP made me think of a diaper sexual fetish that is common among adults. I do not know if a boy as you g as 11 can develop it, but please look into it and learn what you can. I thought of the sexual fetish when I read at how angry your eldest son became when he learned of your snooping around in his room.

It was on the Sexual and Gender Issues subforum on this site that, some years ago, I learned about the fetish. The site has a search function whereby you can put the keyword "diaper" and limit the search results to that particular subforum. Alternatively, use the so-called "site colon operator" on Google - is the keywords "diaper fetish", then type "site:" (site, followed by colon, and immediately after copy-paste the top level URL of this site.