Hi and welcome to this wonderful support site. I hope you'll receive more opinions/advice in addition to mine as the group is filled with experience and good ideas.

It sounds like the ID doctor scared the bejeezus out of you. Regarding the ID doctor, is this someone who works with the BE/NTM population in particular? There are around 33+ BE NTM sites around the US. It's important to seek care from one of those sites as they work with the latest treatment guidelines. Pulmonologists on this list usually have ID doctors to whom they refer. In other words, ID doctors who treat NTM day in and out. It's possible your ID doc is not that familiar with the latest in treating NTM thus the scare tactics as he might not know better? Link below.
https://www.bronchiectasisandntminitiative.org/Find-Care/Care-Center-Network/Find-a-Center
NTM is everywhere. There are a number of ways you can co-exist with NTM in the environment (including water). I'm attaching information which address how to co-exist or reduce your exposure to NTM in the environment. It can be done! It takes some getting used to but it is manageable.

https://www.ntminfo.org/wp-content/uploads/2019/06/NTMSupplementalGuide.pdf (a little dated but still contains good info)