You can disown the person but you can't completely disregard the connection.
And this is where I'm taking this... In my latest book, Not Built to Be Broken, I say the following:
You can make pain about being broken or you can see pain as being a lesson and the people who contribute to it as being your teachers. No matter how you look at it, there’s an investment in brokenness that will never give you a return. You’re infinite, unlimited and you never run out of chances to change your life. If that’s true, you can’t possibly be broken by anything. No matter how bad the situation seems, no matter how grim the outlook appears, you weren’t built to be broken. You were made to be free and if pain is your prison, you are the jailer. No one else but you can do that.
And here's my point: When the person who hurts you most is supposed to be the person who knows and loves you best, you've got to be able to separate your compassion for them from your susceptibility to them. You can pray for someone's change but you cannot deliver them to that change... and you don't have to be their punching bags while they go through the process.
Bottomline: Pray for toxic family members but DO NOT be preyed on by them.