Can a hidden camera really be blamed on his ADHD?

My husband was diagnosed with ADHD in February. He hid the diagnosis from me (he said its a private matter, and he’s very secretive by nature) and I only found out because I found the tablets. 

There’s a backdrop of him blindsiding me with things in our relationship - his impulsive behaviour / not thinking through the consequences is as a result of his ADHD, but hiding his diagnosis was almost the final straw for me. We have two young kids, one of whom is struggling at school - so his diagnosis is relevant and it is not a private matter in my mind.  

We’ve been having counselling since the summer. I thought we were making some progress. The counsellor is vastly experienced in ADHD and ASD; every scenario I give her, she can explain as his ADHD brain. Which is helping me to understand why he is as he is/why he does what he does, but it doesn’t make me feel better about the stuff he’s done.

On Tuesday night I discovered he’d put a spy camera (hidden in a USB charging port) in our bedroom. When I asked him about it, he lied, and promised me it didn’t have a camera in it. The truth eventually came out, I stayed calm, despite being upset and feeling violated. He’s not even sorry for what he’s done. He’s paranoid that I am snooping on him, paranoid because things in his office keep moving (I never go in his office! But we’ve got two kids who do!), paranoid I’ve hired a private investigator (erm, that’ll be a no!), and feels he’s ‘justified in his actions’. I’m at a loss. 

I feel like I’m going insane as I can’t talk to anyone about this who knows him as they all think he’s wonderful, fun, a great dad...

Can this behaviour really be his ADHD, or is it something more sinister?