How to deal with strange family relationships

So ive been looking for ways to deal with my strange family relationships and up to this day (im 19) I havent quite figured it out.

So for context my dad is not in the picture, I grew up with a single mom. I didnt grow up around her family much because of their strange relationship (apart from my grandmother). See my mom was adopted and since she was a child shes been treated very differently from her siblings. She didnt go to the same schools as them, wasnt allowed to eat the same food etc. She was always kinda excluded which I guess made it easy for my family to not really acknowledge me much as a child. They were never there for any birthdays and nothing to the point where in the last few years I saw some of them and they literally had no idea who I was (we are only 7 grandkids so). I wanted to look past that and build a relationship with my only family but now I have an issue.

When my grandmother passed she left behind a pretty large inheritance (villas, apartments, lots of money etc) and before her death she had specified how she wanted to split it. (She never actually got to write a will). When she passed we went back to our home country to bury her and went to the bank to discuss inheritance. Long story short neither me or my mother got anything (in our country adopted children arent garanteed inheritance by law). My little cousin who never got to meet her got stuff, but us nothing. Not a ring, not a plate absolutely nothing. Im to this day still pretty hurt by it because the inheritance was not small it wouldve cost nothing to give us one thing and yet they couldnt.

I know this is long but I want other peoples opinion. Should I even bother with them, does it seem like they care or is it enough to just abandon the bond ?