I agree that is how Alec treats Clary, however they were not supposed to have a pre existing "closer than brothers" relationship. He was and often is a dick to her but that was his relationship with her in canon, at least at the beginning. Maybe I am more forgiving of it because on screen she comes across as even more of a selfish nitwit than in the books, but I digress.
As for Alec being treated badly by Jace, it was even lampshaded by Simon in the episode where Luke was remembering Idris. Simon mentioned that Jace treats him like a dog and Jace gets defensive and says it isn't true without even a slight bit of self reflection. Aside from that, I think it reads as emotionally abusive to me partially because of either the acting choices or blocking choices of many of the Jace/Alec scenes. Jace is always standing straight and facing forward and erect, very assertive body language. While Alec is usually hunched/slouching and often turning his face away from Jace, which is classic appeasing behavior. This could be because the director trying to minimize the fairly significant height difference between the two actors or it could be a deliberate choice to show how much more submissive Alec is. We also see Alec nearly always cave to Jace's request or demands but Jace never caves to what Alec wants, when they disagree. The only time we do see Jace give in, it was clearly a plot device to get rid of the fighter with the range weapon to show how the Mortal Cup worked. I think the scene that really did it for me was at the bachelor party, when Jace was "apologizing" to Alec, he basically discounted all of Alec's fairly significant concerns (lied to him, stole from him, humiliated him, and nearly got his sister killed) and said "I did what I thought was right," insinuating that Alec was wrong for not agreeing with him. He completely invalidates Alec's point of view and opinion by making them Alec's fault for not trusting him, which is a common tactic of abusers. Think about their relationship and the way Jace treats him, if Alec were his wife or girlfriend. To me, it would come across as very controlling (come do what I want regardless of your concerns) and abusive (if you don't agree with me you are wrong and that is why I had to do bad things, because you made me). I know I would be thinking, "why don't you leave that a-hole" and "why do you keep taking him back after he ignores you and runs off leaving you to hold the bag?" Your mileage may vary and that's cool. I'm just explaining why it appears that way to me vs the way it was portrayed in the books. Jace was much more affectionate and respectful of Alec in the books in my opinion than he is in the show. If I hadn't read the books, I would think the two didn't even really like each other.
