Honestly, part of the problem is simply losing perspective. Take some time off (yes, seems impossible when you're the only guy) or more regular breaks will help YOU not freak out over other people being jerks.
Also, work with folks when they don't have a problem to help them understand how to get the best service from you. Reality is, you're an extremely limited resource and when they have a problem, it is in their best interests to understand how to get the most out of you. So, do some training with them, have small meetings, etc. explaining that you're one guy, actually NOT out to ruin their life (it does help if this is a true statement), and want to help them (again...), and this is the best way to make it all work.