Dear sister, first of all, you engaged to him and stayed quiet because he is phyiscally good looking, that is your first mistake. Second mistake was the convertable part, again. You already made two mistakes that I seen many teen sisters here address that they will not do that. My perspective is that you better think again thoroughly, appearances are deciving especially in this time of period. You should always marry a man for his religion. You got engaged on his physical beauty, this marriage MIGHT NOT be sucessful. You might not even like his personality, just because your brother likes his personality doesn't mean you will. To illustrate, if my mom or my brother went out to find me a wife, I'd say chances of resulting in a divorce are 90%, because their personality and other stuff is way different from mine. I think you should have a serious thinking seesion with yourself, will this guy be able to rise my children rightfully, religiously, and will he be a good pious man. You made at lease one major mistake by staying silent at the engagement, hence when you talk to your mom about it, she will bring that up and what will you say. You could win, but its mom, it is very difficult. I suggest you think and write down all the cons and pros of the guy you are about to marry, like someone said in a pervious post. And THINK OF THE RELIGiON, ISLAM! That is what is marriage is about. I would cite Prohpt's hidaths to you, but I am unable to find them since I do not have any books or know any websites currently, but I am sure you know it. Make the right decsioin sister, if it's beauty and his convertable and wealth, it will cost you, but if it is religion nothing will cost you. May Allah guide you to make a right decision, protect you from evilness, ameen. I have one little question, If you don't mind me asking, what is the individual's background the guy you are about to get married to.
P.S: You should also, think about the guy you are about to marry, is he honest and truthful? And when you answer this question, think about is he appearing honest just to satsify you and your mom and your brother? Is he truthful temporary or he is truthful despite anything. You have to think thoroughly sister, it is your life, think about the future and what questions should you be asking and what questions should you not.