What should I do?

We've all seen your work, you have excellent skills. If your current employer fires you for an accident that is clearly not your fault, then take your skills and move on. Your shop isn't the only one busy, I'm in a different trade (electrician), but I've been averaging 60-70 hours a week for over a year now, some weeks have been in the 90-100 hour range. Your skills will translate to a variety of employers, and everyone is looking for people that know their sh*t. You're not going to get the same amount of work done if you're hurting, and being miserable at work starts to affect your attitude and your product.