Yes, endocarditis is one of the worst case scenarios but many would be surprised just how easy it is to get it. One of my old friends had it and it damn near killed her.. (Not my friend anymore cause she banged more than just dope IE my boyfriend)
Anyway.. I'm glad y'all are okay. Never heard of cotton fever/dirty shot killing anyone but I'd imagine its not good for you, and if you get it over and over then you need to be more hygienic when it comes to your IV drug use.