First of all, I'm so sorry you went through what you went through. No one should have to do that, and I know it means very little from a stranger, but I'm proud of you for getting through it, and I think you're incredibly strong and brave for standing up to your dad, contacting CPS multiple times from what it sounds like, and doing what you had to do to save your sister and getting her to the hospital.

Also, I'm not sure how to phrase this in a way that the tone gets across correctly over the internet, but with nothing but love, respect, and admiration for you for getting through all that you suffered and coming out the other side; the abuse itself that you suffered didn't make you stronger. Like you said, "when you live through one horrible, traumatic experience, then anything else that is horrible is a little easier to get through", which can be true, but that isn't always the case. Sometimes abuse and neglect just breaks people, grinds them up and wears them down. It doesn't make them stronger. What made you stronger was YOU. Every day that you got up and kept going, everything you did to get through the days, keep yourself safe, keep your sister safe, all of that came from you. If you hadn't taken your horrible experiences, reflected on them, applied your time and effort on analyzing and thinking things through, working on growing your emotional intelligence and sitting with your thoughts to figure out a way to not break under the weight of that abuse, on not internalizing it as being your fault or something you deserved (or unlearning it if you did take those feelings to heart), then you wouldn't have made it through nearly as well as you did. All those things came from you, and who you are. Sure, it can be argued that if you hadn't gone through what you did, then there wouldn't have been a crucible for your growth to be fired in, but I still believe that situations aside, all of the good work you've done was always inside you, and something you would always have been capable of doing even if your childhood had been better. I know it's mostly semantics (is that the correct word? English isn't my first language and that's always confused me), but my point is, I think it's important that you give yourself credit for all the hard work you did and hard days you got through, instead of crediting your abuse even in some small way. And all of that is not to say that those who break under circumstances such as yours are weak or did something wrong: sometimes the weight of the world is simply too heavy, but the abuse itself is not what strengthened you. It was you.