So my future MIL thinks I'm a gold digger but...

Lizz
So my fiancé's Mother "occasionally" gets drunk and says things that insinuate that she believes I don't really love her son, that I'm a gold digger who just wants to get pregnant and trap her son so I don't ever have to work for anything.
I'm 24, I've owned a house for about 2 years that I bought for 55k and am about to sell for 90k. Granted I only make about $20k a year so I live pay check to paycheck. 
You can see why she might think something right?
Well I've known that I'm a partner in a property that if I sold my share I could stand to make about 50k.. But I make a little income off it ever year, and it's my grandparents property so I have no intention in selling my share to the banks. 
However.. I found out a few hours ago that when I turn 25 (in January) and I stand to recurve a inheritance. Anywhere from $40-80k...
Is it crazy that I have no idea how to feel about this because of what my fiancé's family thinks of me and my intentions?
I should be excited, but idk if it hasn't set in yet or what but I'm kinda numb.. >.>
Any thoughts/advice?