Why does my dream world always collapse the second I realize I am actually dreaming?

I have been practicing WBTB for three weeks now and I finally achieved lucidity last night. It was incredible—I was standing in what looked like a perfect replica of my childhood library, feeling the texture of the old wooden shelves. But the moment the realization hit me that 'hey, this is a dream,' the entire room started to dissolve into a blurry, grey static. It felt like a low-resolution video game failing to load. I tried rubbing my hands together like the forums suggested to stabilize it, but I just ended up waking myself up with a jolt. It is so frustrating because the clarity was there, but the sustainability just isn't. Does anyone else struggle with this 'collapse' effect, or am I getting too excited and spiking my heart rate? I want to explore, not just get a five-second flash of awareness before reality crashes back in. How do you guys stay calm enough to keep the dream environment intact once you gain control?