My general advice is stick with family. You only get one that is recognized legally, socially, biologically, and every other -ally. No matter how annoying, family is always family.
Is there a time to walk away from family, or a friend, or even a spouse? Or are we to stick it out no matter what? If there is a line that once crossed makes it Okay to walk away?
The problem is that we are not all the same. Every person is different. Each has different strengths and weaknesses. Others are more open to change while some just aren’t. Situations vary. So there is no magic formula into which you can plug a few numbers and know the answer nor is it as simple as Ann Lander’s constant advice, “Are you better off with or without this person?”
So there is Jesus, the perfect model. He knew that Judas was going to betray Him. He knew that he was a thief. He loved him anyway and was thereby able to bring good from Judas’ evil action.
There are many persons we could site who did this. One of my favorites is St. John of the Cross who was treated miserably by his family and fellow brothers in his order. For what was done to him, if today it went to court, many of his confreres would be jailed. But he loved them, stuck with them, and today his love is still transforming the Church.
But must we always stick it out? Matthew 7:6, "Do not give dogs what is sacred; do not throw your pearls to pigs. If you do, they may trample them under their feet, and turn and tear you to pieces.” Or Luke 13:27: "But he will reply, “I don't know you or where you come from. Away from me, all you evil doers!” (I may be forcing the context a little, but I think there is a point to be made.)
A lot of discussion and discernment must take place with the appropriate persons. But in the end it comes down to this: The motivation must be love.
Did you find out that your spouse is a child molester? It may be that love for your children may call you to part ways.
Is family pressure so great and your strength only so much that your faith is in danger of being snuffed out? It may be that limiting exposure is necessary in order to preserve your loving relationship with God.
Is your spouse an alcoholic and not seeking help and they need waking up? Would stepping away help them to realize what is happening to their life? Can you do it in a loving way with the motivation of them finding healing?
Tricky, tricky questions. As you can see, we could come up with a billion scenarios all with varying factors. And there will always be people on both sides of the fence. “Never, ever give up on anybody!” and “How on God’s green earth could you suggest that somebody stay in that abusive situation?!”
Prayer. Discernment. Consult. And most importantly, find the loving motivation.