You do not have to tell others what you experienced with your father. Also, you are not responsible for anything he ever did either, and whatever he did to his sister is his and her problems to solve and resolve and anything your father did never means you might do the same either.

The fact that you are looking at all of these issues and you feel so overwhelmed that you even feel suicidal means you need to find a "trauma" specialist that can help you SLOWLY process all of this where you can walk away from certain things mentally and emotionally understanding that there is really nothing you can do to change others, and the most important thing for you is to come to terms with whatever hurt and affected you and finally heal and get so you can move on with your life instead of being stuck and feeling so alone with all of this.

One of things I myself learned is not to tell the very same people that failed you in the first place, all that will come of it is more hurt and failure. It's much better to talk to someone who CAN help you work through these challenges where you can slowly process them and find your OWN sense of resolve.