I'm so very sorry for your heart-breaking loss- from your previous posts, I had a feeling- a bad feeling- about where this was heading, but you never know for sure.
So this wasn't actually proven by the vet to be Nido? I don't think bioactive had much to do with this. I suspect you came home with an already-at-risk-&-most-likely-sick snake- you got off to a very unfortunate beginning with snakes. If it's any consolation, the second snake I ever got (not long after the first but from a pet store) was sick & I (& the vet) were unable to save her. But here I am, with decades of many snakes in my life since then, so no, it's not "over" unless you want it to be. It wasn't your fault- even though you made some mistakes & could have done things better, it's unlikely you could have changed the outcome. Some things are just very hard or impossible to treat- & this snake was already weak- & really was not ideal for a new snake-keeper either.
But yes, you have a lot of cleaning to do, & I'd wait a while too. Toss out anything porous like cork & wood- sorry, it's just not safe to clean & re-use them.