There is a simple idea many people, including myself, struggle with. You are not responsible for the actions of other other people, and you have no direct control over anyone.
It's important to make the distinction that you do have responsibilities to people, but not for them. You have a responsibilities to your children, family, friends, and to humanity, but ultimately they make their own decisions. So if your kid kills someone or stays in an abusive relationship, if your spouse cheats on you, if your friends betray you, if your friends drinks themselves to death, it was their decision. The decisions you make and the way you treat people can have influence on others, but everyone, including yourself, is responsible for their own actions.
There is a phrase in the recovery movement: give us grace to accept with serenity the things that cannot be changed, courage to change the things that should be changed, and the wisdom to distinguish the one from the other.