Mom and Grandma died when I was 16, just now told about inheritance at 21?

Location: I’m in California, my mom died in Mexico and my Grandma died in Maryland. This is being managed in Maryland for reference.

Basically my mom died when i was 16, I lived with my adoptive father (her husband) and my grandma died a month afterward. My mom only has 2 other siblings, her brother and sister, and they were my grandmas only family. Well my adoptive father sucked, he stole all my survivor benefits from me and kicked me to the streets. So from ages 16-21 I have been living paycheck to paycheck, didn’t ever see university as a possibility, and had all but given up.

Just yesterday, my uncle contacted me for the first time since I was 16 to tell me I’ve inherited everything my grandma was going to give to my mother… a little over 200k. This is an amazing thing and I’m shocked. I can have small portions of it monthly, but will get it all at age 22. (allegedly this is what they’ve told me)

But why wait so long…? The only other time he’s contacted me was to text me when my mom and grandma died. Not even a phone call. This was the first time I’ve ever spoken to him over the phone. They’ve been letting me struggle this entire time. I have this feeling like they were waiting for me to off myself or something so they could keep the money. It’s weird right?!

I know the basics like don’t sign anything without legal advice and I’m not telling anyone about my inheritance but was this legal? Was it legal to hide this from me?