My Sister (24F) got together with her boyfriend (26M) less than a year ago. I (26M) never liked him, neither did my father or stepmom. He's always been disrespectful and a drug addict that we just couldn't like, even though we tried.

We tried our best to like and accept him, but that that became impossible after two events. Almost 2 months ago, my sister got into a car accident. Her bf was the one who called me, letting me know that she had an accident and was in the hospital getting checked. I drove over 3 hours that day, and waited for more than 6 hours in the hospital. He didn't bother to show up. In those 6 hours, I had him on the phone for three times. Every time, I asked him if he knew what happened and every time he told me he didn't have a clue. When I finaly got to see her, she started crying on my shoulders when she realized he didn't show up, telling me she needed to break up with him. That's when I found out that he lent her a car with no front brakes, and that was the cause of the accident, injuring two other people. I gave her my best advice possible and stayed up late. Drove her to my father's house. She then disappeared 3 days later and decided to "not give up on him".

Later that month, on a Sunday night, while I was already sleeping, she called me sobbing. Long-story short, they went out with friends, he got drunk (regular occurence) and told her that even though she is the woman of his life and wants her to have his children, he wants to fuck other girls, since he hadn't had many GFs before her. He then proceeded to get in the car, drunk, and threatened that's he'd lose it if she didn't get in the car. I, again, drove 3+ hours that night, picked her up, drove her to my father's just for her to, again, disappear the day after and give him another chance. (At the time, they already knew about the pregnancy - I didn't)

Today, I called her to let her know I wouldn't be joining her for her b-day party. I decided to be honest with her and told her that, even though I have to accept their relationship, I don't want to, neither do I have to support it in any way. She told me that it'd be important for me to be there, since she had a big announcement to make. I immediately figured it out. She's pregnant. The thought of my little sister's kid, having a father like him just made me feel sick. I tried maintaining calm. I told her I'd prefer not to speak about it, to avoid saying something I'd later regret. After she kept insisting, I told her that I wanted to be happy for her, but at the moment I just can't.

She told me that I was being unfair and that's when I exploded. After years of her being the preferred one amongst the three siblings, after years of me protecting her, after years of me being there for her when she needed me the most, after years of me being the one who had to clean up her mess and suffer the consequences for her actions, I just couldn't accept her saying that I was being unfair.

I really tried keeping this story short, because trust me, there's a whole lot more to it. Specially stories about her boyfriend that just shows how horrible of a human being he is. But I just need an outsider's opinion. Am I the asshole?