Does anyone else find that their practice falls apart during exactly the moments they need it most?

When things are going fine I'm great at being mindful. Peaceful mornings, low stress weeks, easy days. I'm present, I'm grounded, I notice my thoughts, I respond instead of react. Gold star, great job.

Then something actually stressful happens and every tool I have goes straight out the window.

Got into an argument with my brother last week and I didn't pause, I didn't observe, I didn't take a breath. I just reacted exactly like I would have three years ago before I started any of this. Full autopilot, full emotional hijack, said things I didn't mean.

Afterwards I sat there thinking what was the point of 3 years of practice if it disappears the second I actually need it? It's like training for a marathon and then your legs give out at mile 1 on race day.

I know the answer is probably that the practice is working in subtle ways I can't see in the heat of the moment. And I know that gradually the reactions will be less intense or I'll recover faster. But honestly it's discouraging to feel completely at the mercy of your emotions during the moments that actually count.

How do you deal with this gap between your practiced self and your reactive self? Does it ever actually close or do you just get better at the recovery?