Hey @1-Bob-2
I want to acknowledge the strength it takes to recognise that this split is a good thing while navigating the very real pain it causes. 15 years is a massive chapter of your life, and even if that chapter was filled with drama and anxiety, your brain has become wired to respond to her needs and crises 💚
Since you mentioned ADHD and a tendency to overthink, it might help to look at why your mind is looping on her. Often, high-conflict relationships provide a constant stream of dopamine and adrenaline (even if it's negative). When that stops, an ADHD brain can go into a sort of dopamine withdrawal, causing you to hyperfocus on the person to try to recapture that intensity. This is coming from someone who also has ADHD and overthinks, and has been in a few relationships that were not healthy.
When you have the urge to think about her or check in, your brain is trying to look for a place to put all that energy. I would really recommend writing a burn letter or two. It can be physical or digital, but it's a letter you never send. You can say every mean, sad, or anxious thing that you're thinking. Once it's written, you can delete it or destroy it by ripping it up, burning it, or otherwise disposing of it.
For us folk with ADHD, silence at night can be a vacuum that sucks in intrusive thoughts. I would recommend playing background noise, like brown noise, or an ambient-soundscape video; even the sound of a fan can help. It gives your brain enough "texture" to focus on, so it doesn't wander back into those thoughts.
ADHD also thrives on novelty. Meeting new people can feel like a high-pressure chore. Instead, you could try a micro hobby that has a quick finish line, like a Lego set, a paint-by-numbers kit, or learning three chords of an instrument that has always fascinated you. This serves as a replacement dopamine hit, completely within your control.
Be patient with yourself. This is not a straight line, and having a "bad" night where you overthink does not mean you aren't making progress 💚