I’m so sorry, OP. You don’t deserve to be treated like this, especially not 2 months before the wedding, and after such a long relationship.
He may make more money than you but the reason for the assumption of the 50-50 division of assets acquired during a marriage is that when one person brings in less money they usually contribute a lot more in other ways (looking after children, doing more house work etc.). What he’s suggesting isn’t fair. Oh, and btw, he wouldn’t be left with nothing if you split your assets 50-50 – he would be left with 50%! I would hardly call that nothing.
And don’t fall for that “if you don’t plan on divorcing me anyway none of this matters” trick. There’s so much more than divorce at stake here. The death clause, the division of assets while you’re married? Both ridiculous, both unconnected with divorce. I agree with a PP, what if you become ill and are unable to work? You won’t bring in any money, that could very well mean you’ll be married and literally starving if his family decides you’re pretending to be ill so you can mooch off of him and forbids him from giving you any food! Yes, I know this is extreme, but I wanted to give you an example as he seems to be very much under the influence of his family. Besides, it’s knife that cuts both ways! What if he becomes ill and cannot work anymore? If you divide your assets 50-50, that means whatever you make is his too. When you don’t, you could very well decide you don’t need to support him. You don’t sound like the kind of person who would do that but that is what you could do, under such provisions. I don’t know about US laws though, where I come from, it’s a spouse’s duty to support the other spouse who, without any fault of their own, cannot support themselves.
I’m a lawyer too and I have two brothers so I can, to a degree, understand his sister for trying to protect your Fiance (but what she’s doing defies all logic). I don’t, however, understand him for NOT trying to protect YOU! I’m sorry but I have to say this: this does not look good to me at all. Even if you marry him, I seriously doubt you’ll be happy with such a person. It looks like his family has taught him to look at everything through the money loupe. In my experience, only extremly emotionally starved people have such a way of looking at the world.
I’ve seen such things go to such extremes as “you’re not allowed to sit on my sofa, I bought it” and “you’re not allowed to eat this cheese, it’s mine because I bought it”. I’m not saying it would come to that in your case but once a relationship becomes all about who owns what, things can get absurdly out of hand very quickly.
Please, please, please, do yourself a giant favour and don’t sign anything. Your FI’s family, and sadly, your Fiance too, are trying to bully you into signing something that will hurt you. I would rather be single for the rest of my life than be married to someone who doesn’t care if he hurts me as long as he gets to keep his money. That’s not love.