I missed a diagnosis :(

I can't give many details because the owners have threatened legal action. But I missed a diagnosis and the dog ended up at the ER and was euthanized two weeks later. I feel terribly for the family's loss and my mistake, but then also stressed about my first possible board complaint. I have watched webinars on the disease in question to make sure it never happens again. I need reassurance that I'm not the only one who has gone through this :( I definitely understand why vets have such a high suicide rate, this is devastating for me. I've never lost a patient due to a mistake I made and I've never felt so responsible for a death before. I tried to get the client to bring the dog back in when I called to check and she wasn't doing better and they declined. I have been practicing less than 5yrs if that is relevant.

Edit over a month after the initial threats: No complaints yet. I know there is still time but so far my practice has not received any notice of legal action. -the most personal question received was nearly 100% accurate, yes it was Addison's.