Worst example is friend who, after being hospitalized for accident while car surfing, died car surfing again. I wasn’t present for either event.
Second worst is dude with head injury (unrelated) started talking about crystals and toxins and juice fasting. Called him out one day, and it was catastrophic. This one is still alive, at least AFAIK.
Third, divorce. You will find out who your real friends are when you get divorced.
I’m so sorry. I strongly suspect this happened to me as well. To this day I’ve never mentioned the evidence I had of her infidelity to anyone, because I’m a better person that she is. My former friends likely discovered this for themselves in due course.