I've struggled with this before my self, where I would run a disastrous session and feel like shit about it for a while after. It happens to all of us, it's not a personal shortcoming- We all make mistakes, and your friends aren't mad at you, and they understand you. 
Always have an exit strategy. I've practiced donning my gas mask and packing up all my books and materials in the time it takes for a standard SOLAS smoke signaling device to burn out.