It is okay to hate a "family member." It is okay to hate the way they make you feel. It is okay to hate the words or the looks. The times they ignore you, when you need someone there. The way that they control you, far more than anyone ever should. It is okay to hate going home to family members who do not value you.
Our world tells us that the blood is thicker than water. Well, guess what? The real phrase is, "The blood of the convent is thicker than the water of the womb." Do you know what that means? That means that relationships formed by choice are stronger than those formed by birth. Birthing a child does not entitle anyone to love nor respect. They have to earn it. If they do not treat you with love and respect, then they do not deserve it either.
Family. Family is a word that is taught incorrectly to children. We assume that because these people are with us in our genes that there is some higher level of bonding than with any other individual, but that is simply an assumption. A family is a group of people who came into your life, and never left, no matter what happened. A family is a group of people who you love and trust, but who also love and trust you. They give you a place in their hearts that matches their place in yours. It does not matter what point in the story they entered, because once they entered, they never left. They did not have to be there since day one.
Your family is a group that you decide. Maybe your parents are there, maybe they are not. They do not have to be. It is okay if they aren't. Nothing says they have to be. Do not let other people tell you that your family is not your family simply because they weren't there since your birth, or because they did not have a part in said birth. If your pets can come into your family after many years, and stay a part of your family, when they very clearly are not blood related, then why can't another person? Hold true to your feelings, and the end of the day, those feelings are what is going to matter to you. If someone is making those feelings hurt, then kick them to the curb! You do not have any requirement to tolerate them! A real family would not ever make you question your worth.