Ever had one of those moments?

I have to say in my 10+ years of riding I have never had a moment freak me out so badly as this moment did today...
So Cash and I have been on our A-game lately!!(knock on wood!) and have been having rock star lessons and I have been feeling totally prepared for this upcoming show! (13 days away!! So pumped!) but we had our lesson on Thursday and despite it feeling more like going mudding the. A riding lesson it went awesome!
So I got out there today (friday) and decided to do some flat work in the ring then go for a walk in the field and just kinda hang out with him. So I got down to the arena and footing looked pretty good, especially compared to yesterday, I mean it was drying up a bit but it wasnt really sloppy and it was actually fairly cushy so I figured it was good. Got on and obviously walked for a bit and then went to our trot. For about 15 mins we trotted, lots of lateral work and spirals and big circles and small circles and all kinds of things and per usual he is being awesome:)
Everything was cool and I just kinda loosened my grip on my reins and sat way back in my seat and told him "woah" when WHAM!!! Next thing I know I'm on the ground!
Cash tripped over his own feet, while slowing down... in that split second I saw his whole neck and head fold completely under to his chest and touch the ground...
When I got up he was stark still and had his head cranked towards the left side of his belly were I was standing in a very cramped looking position, and after vigorously rubbing his neck he finally relaxed his neck and I could walk him around. We got up to the barn and he's got a small scratch on his nose and on his leg but very superficial. He's lucky that's all that happened! He could have killed himself!! And he scared the snot outta me! That's for damn sure!
I'm alright so far... a little bruise and tender all over but fret not! I'll live:)
God just to know that he could have been seriously injured from that scares me so badly! And the fact that if I didn't have a helmet on I would have been toast! Just goes to show you that you can know your horse to the T and all it takes is for them to have a big enough miss step and them trip and you could be sent flying!
I'll keep you guys updated on the show though! 13 days left!!!