Another here who feels your pain and has been in a similar situation. The hyper awareness of the noise of a can opening is horrible. My ex used to drink on his way home (I now know) and come straight in to open a beer stating an awful day at work and he was just having one to relax, this was so I didn't smell the previous pints on his breath.
He would also express either disgust at whatever I was cooking or say the pasta dish needed garlic bread, so would walk to the local co-op for whatever he decided was needed. He would call in the pub or the off licence and down vodka. I always thought for the fuss he had made about getting garlic bread, it was odd he only ate one slice! Plus he would almost cause a row to go out for a walk. To all intents and purposes, he looked like he had had one or two beers in an evening, he is fairly slim, so I thought some days alcohol just affected him differently.
I did realise he was drinking more than the one or two he appeared to drink eventually and tipped out the recycling bin and found 60 cans from 10 days (& he had been out on work Christmas parties 2 nights and not drunk and had come in absolutely steaming) so effectively 8 nights empties. I didn't realise until after I had left and had counselling that he was loading up on his co-op shop trips, he since confirmed this. He even blamed our neighbours for stealing the crate of beer he had left by the back door (one at a time!!) the Christmas that we split up.
He was always promising to cut down and have drink free nights in the week. The reality was he was the most bad tempered guy ever on the odd occasion he really didn't drink, plus went to bed very early. He wasn't always like this, he used to be the really fun, chatty lovely guy everyone sought out, he seemed to deteriorate from that guy very quickly to the secretive drinker. I found empty gin bottles in the wardrobe and said enough as like you, was already a single parent effectively, but with this horrific alcoholic child too that took up too much head space.
After I left he went to rehab (twice) he lost his good job and has had a variety of odd jobs that he has either walked out of due to a disagreement, or been told to go due to drinking on the job. He has been arrested/prosecuted for drink driving (over 4x over the limit) and has told me many times he is about to take his life (he hasn't) He found a new victim/girlfriend relatively quickly after I left who must have issues to still be supporting him and he rarely sees his children as it interrupts his drinking/or as he says he doesn't want them to see him when he isn't good. He has frightened them in the past with sudden outbursts, but to be honest, for quite some time now I only allow him to see them if I am there too (if they want to see them) as it is the only way they feel secure around him now.
I am so glad I left when I did and my children are so much better with just me. They have had it explained in an age appropriate way that he has issues around alcohol and it is not because of anything to do with them etc etc. Had I left it longer, I think it would have impacted them so much more. In reality, he was only this bad in probably the last 6 months of our marriage before I left. He was an utter nightmare to divorce though as buried his head in the sand about any correspondence. I also had breast cancer after leaving, I believe the stress of his behaviour impacted my health considerably. I am much much happier on my own with my fabulous children. He still rears his head now and then and after any interaction with him, I just feel utter relief to no longer be with him and that I am free of his drama.
All the best x