how do I stop over-stressing over bugs?

How to deal with over-stressing over bugs?

I just got promoted to senior after only having worked as a developer for a year. I work as an IT consultant where I directly communicate with the clients and I am the only front-end developer working for a start-up. I feel that I can handle communication and most of the development work very well. The problem however is when things go wrong, I tend to over-think it. If something does not work and I can't figure out how to fix it even after hours of attempts. When this happens and my workday is over, I spend pretty much all my after-noon stressing about the issue and how I have nobody to go to for help. I just keep fearing that the client will think I am a failure or that I'll have to involve other developers because I am not good enough. The problems always get solved, often with just minor tweaks but in my head I just over-think and assume that I have majorly fucked up and I can't stop… Right now I am awake 5 in the morning writing this because I am having issues deploying my code and getting a bunch of errors suddenly. And now I am losing sleep over it… I was just hoping to hear from more experienced developers about how to handle such situations. Thanks in advance