Cancelling something you'd promised because you got overwhelmed
ADHD parent behaviour
What to do right now
You promised something and you're not going to be able to deliver it. Tell them now — don't let them discover it by it not happening. "I have to cancel [the thing]. I know I promised. I'm really sorry." Brief, honest, no excessive explanation. Then find the smallest possible version of what you promised that you can still make happen.
What your brain just did
Your body
The weight of the promise you can't keep is sitting in your stomach. You know the disappointment that's coming and you're dreading it more than they'll experience it.
Your brain
ADHD brains overcommit because the future feels abstract and the desire to please is immediate. The promise was made by a version of you that didn't account for the executive function cost of following through. The gap between intention and capacity is the core ADHD experience.
What this did
Your child learns to expect disappointment. Over time, this erodes trust in your promises. The repair: make fewer promises. Say 'I'd like to' instead of 'I will.' And when you do cancel, acknowledge the impact directly.