Wow, your placement sounds exhausting! I don't know if I could cope with that. You have all my admiration for getting through it. Be assured, it's NOT you, anyone would feel stressed under that kind of pressure.
Try not to let your mentor's manner get to you. I've had one mentor who was cold in her manner, the other was politely friendly...although I was a lot happier with the second one, as long as they're fair and get you through the placement it doesn't matter does it? You're only together for a few weeks and not wedded for life after all!
I'm still astounded at how hard you are working. You MUST be a natural teacher to be managing to teach on top of everything they are throwing at you. Don't give up, you're so close now!