Hi,
I had the same problem - I was pregnant with my son, engaged but unmarried to the father.
The will stated any blood relative with the name xxx (surname) would inherit (again, like you it was a huge amount of money) and just because my now husband and I were not yet married - the wedding was a few months after the lady died, our baby did not inherit a penny.
The rest of the family said they would look after our son's interests and 'make it right' - again, like you nothing has happened, not even a provision in his grannies will - when it comes to money don't trust anyone to do the right thing morally because they won't - fight for it - even if you hurt your relatives feelings, they would do it for their kids!
Life isn't fair.