AITA for telling my brother he doesn’t have my permission to marry me off to his best friend?

My brother has been asking me for over a year now if I would date the guy he’s basically considered his shadow. It got to the point where I started to feel uncomfortable with how much he kept asking me over and over and over again. He wouldn’t drop it until I finally snapped and told him NO I WILL NEVER DATE HIM, AND IF YOU WANT TO HAVE A SISTER THEN STOP ASKING ME.<br><br>He finally dropped it. Or at least I thought I did.<br><br>Three weeks ago, my parents went to their vacation house to visit with my uncle and his family. The last night they were here, my brother tells me out of nowhere that-<br>• “You know (name) is going away for a few weeks. After he comes back he’d like to date you. And maybe hopefully get married this year after that.”<br>• “No, I don’t think you understand I’ve said no, multiple times, I’m not going to say yes.”<br>• “No, I understand sir”<br><br>And he just kept referring to me with manners for the rest of the night like I was an old lady or something until he inevitably ended our night off by saying “You know he’s really in love with you. I have his word and promise that he’s not going to disappoint you, treat you badly, or leave you. If he says yes to marrying you, then you will be his wife for life and he’s going to hope for you to be the mother of his children. If you don’t want to marry him, that’s fine but your life will not be better than living with him. Don’t you understand? He-<br>• “I said no. If he comes back and asks me out himself then I will say no myself.”<br>• “He’s not going to ask you sir. Because you’ve already said yes.” <br><br>And he just shut down any attempts I had to deal with him further. He just refused to hear anything I had to say about anything ever since. If you want food go find it yourself. If you want to ask me anything too bad. If you want to get in your car and talk to me you better get off my lawn. That sort of thing. I think we’ve only gotten 2 sentences into a conversation since then. <br><br>That was three weeks ago. I was going to apologize to him like I always do when he’s upset about me saying no. But he’s made all these diamond studded decorative items specifically to give to my future husband. I don’t know what to do. I don’t want to marry this dude. I don’t even want to date him. And I think my brother is really going to disown himself from me if I don’t. But I don’t want to be married off to a person I’ve said no to. What do I do? Should I just tell him no and let things be like this? AITA?<br><br>Edit because so many people kept asking: My brother and I are both adults in our early to late 20s. Yes diamond dust decorative items are a thing, and yes diamond dust can be sold for a lot of money. My brother sells stones in our hometown. My uncle works in construction in our capitol.