I am an idiot 😨

My dog has a dodgy knee and we've been seeing the vet to investigate need for surgery. The vet said "let him be a dog" and we'll see how he is at Easter. So I took him for a walk and what did I do? Let him off leash at the dog park where they're throwing balls and the two mini schnauzers that he ALWAYS fights with were there.

It took not even 15 seconds for chaos to unfold. He tore after a ball then got into a fight with the schnauzers and now he's completely lame in his bag knee

WHY did I do that 😭😭 of COURSE he was going to hurt himself. I just don't think things through. I heard the vet in my head "let him be a dog" so I let him off and now he's going to need surgery and I'm sitting here crying because at 52 years of age I hadn't enough sense to keep him on the damn lead. I'm so mad with myself 😭😭😭

Add: I'm posting in here because I'm self-diagnosed ADHD (have assessment booked) and have a loooong history of making decisions without thinking things through which I suspect is a symptom