"Public domain" isn't a smart way of saying "things that people have seen publicly" it's a legal term. You're confidently wrong about every single point you've made here. Including the first: if you send your boyfriend nude pictures, and also post them on the internet for the public to see, it remains a violation of copyright for him or anyone else to post them without your permission, and damages can be claimed.
More damages could be potentially claimed if the pictures your ex are posting are pictures you sell commercially, in fact, because you've demonstrated that those photos have value and that you depend on your copyrights to make a living.
You are repeating what rest of us know but the outcome here is exactly the same as you would when you declare it a public domain. You lose control over its distribution.
You are also wrong on the scenario with leaked photos. The partner who leaked is liable not the rest of us who view it and share it.
Your last sentence also couldn't be further from the truth. Someone who is making ad revenues also isn't at fault and compliance with DMCA notice would be enough for them to continue operating.
More damages could be potentially claimed if the pictures your ex are posting are pictures you sell commercially, in fact, because you've demonstrated that those photos have value and that you depend on your copyrights to make a living.