NTA I have a hard time believing a smart, successful person would make such a large mistake, like not changing the beneficiary of soooooooo much money. If he wanted it changed he would have changed it. Everyone can make assumptions about what the brother would want but op is following his brothers actual wishes he made legally binding. Op if you read this I do think it would be an amazing gesture for you to set up each of your brothers children with a college trust and do what you can to be there for them and make sure they get a chance to learn who their father was. Make sure they know his love and generosity helped you start a family so they could have their cousins. I realize my opinion may not be liked by a lot of people but I think following the brothers wishes laid out like he wanted is the right thing to do. I don’t think it’s fair to make assumptions of what he would or wouldn’t want if he already made his choices clear. It’s just a crap situation all together tho money just makes people act crazy, which is why I always say follow the will. There’s no room fighting if the will states things out clearly.