I don't know how to deal with her and this money. Do I tell her?

No. Don't listen to all the people telling you to tell her about the money. She wanted to marry you before you inherited this money so that should be great for both of you. Telling her about all this money will change your relationship, possibly for the worse, when your relationship is already great since you are both going to wed. Talk to a lawyer and have them advise you on how to keep the money to yourself and how to hide it from your soon-to-be wife. You should probably set up a separate bank account with all of the inheritance money that only you can access. If you can't hide the assets that you are going to inherit then just tell your wife that you inherited the assets and some money from your sister. Say that you inherited the assets and only a fraction of the $2 million + that you really are getting. Does your fiance even know that you had this sister? The answer to that could change everything, really.

Anyway, it's your money and if you plan on holding onto it as generational wealth then keep that money to yourself and use it at appropriate times down the road for retirement and/or for your children's education or to give them as inheritance. This is life-changing wealth you've come into and you should look out for yourself first of all and then spend some of that money with/on your wife when appropriate so that she can reap the benefits of the inheritance as well, without knowing where the money is coming from.