Detachment is a process that's a part of the long process of healing. It's a roller coaster ride that no one ever wants to ride.
It's why our cowardly POS ex's chose not to ride it. Rather than deal with their issues they cheated. Rather than process the loss and feel the emotions that go along with something so profoundly life-changing they use their maladaptive coping mechanisms to ease their pain (and inflict more on us).
But you will heal. He will rot and fester on the inside. He is just moving on to the next failure in his life.
I think I understand how you feel. My stbx was happy-go-lucky when I kicked him out. You would have thought he was packing for a trip instead of moving out of the home his 3 young children lived in. The only thing he said that he didn't like about what was happening was that he "hated moving". Meaning he hated having to pack, carry and do general moving stuff. I was confused as hell at the time. It was like we were in parallel universes. My family was being torn apart and my children's lives changed forever while he was riding off on a rainbow shitting unicorn to the land of glitter farts.
But you know what...I'm feeling better. I have my down days. I'm overwhelmed sometimes. I'm often unsure, insecure, angry, bitter, etc. etc..but it's SOOOOO much less than at the beginning of this process. I'm far from healed but when people say it gets better, they're right!
He on the other hand is a hot ass mess! He's angry at the world but me in particular because he will never allow himself to be angry at the right person (himself). He is creating an unbelievable financial crisis for himself. He is alone, has no personal life (so he tells despite the fact that I don't ask and I DO NOT CARE), he is very overwhelmed with basic things like managing his own money or having overnight visits with his kids.
Rather than focus on himself and fix things so that his life will get better he is focusing on me and making me the culprit because it allows him to ignore what he should be feeling about what he has done and what he's still doing.
Your WH gets to by-pass the emotional turmoil for now but eventually he will have to face what he did. Or if he is personality disordered he'll likely just fuck himself over on a regular basis with no clue that he does it to himself. Either way he will have some tough times ahead and won't make the necessary changed needed to be a better person who lives a better life!
As far as him invading your space as if nothing has changed between you two, my NPD ex is/was the same way. I had to learn to go against my nature and learn how to set clear and definitive boundaries. My ex expected the same treatment he was used to despite what he has done because in his mind his actions are always trivial (no matter how obviously offensive and hurtful they may be) and the REAL issue is ALWAYS, ALWAYS how I respond (any negative response = bad).
Ignore him as much as you can right now. I find that I'm still at the point where a phone call with him, face-to-face contact, or even too many text messages in a day still sets me back. The less contact I have the more peace I feel. I know I've had too much contact when I start to feel anxious and overwhelmed and then I make a point to have as zero contact with him for a day or two even if he texts me something he deems to be "important" (it rarely is and it's NEVER so important that my not answering for for a day or two would make a difference).
(((numbandnauseous))) the only "tossed-aside piece of trash" is him.