I hate him, but then I love him

Why do I let him treat me like crap? We have the biggest hate-love relationship.
One minute I wanna kill him, literally kill him. He gives me the biggest headaches. And I just hate him. Hate him so much.
But then other times he's my best friend and I love him so much.
But he takes advantage of me. Takes advantage that I love him even after all the things he does. And expects me to forgive him every time. Doesn't leave me alone when I try to show that I don't need him and that I don't care. He never takes no as an answer. "Please, I'm your brother, I'm sorry".
I'm getting fed up with this weakness I have. The biggest weakness; forgiving those that don't deserve it. I always let him win. I let him think he's won by my giving in.
He acts like he's my dad, making me feel like the worst person when I make the smallest mistake.
He's always right in his mind.

Why do I always give second chances to those that hurt me? I guess it's because I fear that if I don't, they won't stay in my life. That's another thing, I love the good side of our relationship we have and I never wanna lose that. But then again, he's the only one who's ever hurt me the deepest. The only one who has made me shed the most tears. But he's also the only one who knows exactly what makes me smile, what makes me laugh. We've been through hell together. Sigh, my life is such a big tangle of emotion.

Now I get it. In my blessing it also says how I have a kind and forgiving heart.
Blessing and a curse.

Forgiveness is my biggest weakness. I give it too easily because no matter what someone does to me, I still see the total good in them and I can't bring myself to stay conflicted with them. I hate conflict and being involved in it. That's why I can never take sides.

I'm too nice for my own sake sometimes.
Seriously the biggest headache right now.

Sometimes I feel like I live in a bubble and I can't get away from all the things that make me feel confused, angry, upset, every emotion. I just want to take myself out of that bubble, just for a moment, and forget everything. To just not have to think or feel anymore, just for a moment.

Bless whoever ends up being married to me. Like seriously.
A guy with the biggest patience and understanding with my daily mood changes and emotional baggage.
Whoever you are, thank you for putting up with me in the future.