Money frustration

Elizabeth
Need some advice. 
Long story short:
Grew up with a single mom home. Never really had much.
My brother two years ago upgraded his house for a really big house and borrowed 60k interest free from my mom. They didn't tell me.
I eventually found out and didn't really care.
But now that I'm pregnant I feel more resentful, I think because I'm thinking about wanting to provide for my child... My brother will save a lot of money on interest on his mortgage, and he gets to live in a way bigger more luxurious home. 
My home is cozy, but small. We cannot afford to upgrade it.
Am I being petty? I don't want my mom to give me money. I really don't. I just can't shake the frustration that they left me out (sorta feels like a betrayal)