My(26M) GF(26F) hid her family background from me , feeling betrayed. Is this justified from her side?

My LDR GF(26F) and I(26M) recently convinced our families to meet each after a lot of struggle, her parents came and went but the whole thing felt a bit vague and off to my parents, especially about the background of their family.

My father asked his friend who lives in my GFs town about the family to the locals and turns out their wealth is largely created on GAMBLING. They have shops as well but majority of the wealth is from this gambling venture, it is like generational gambling.

Surprisingly i don't mind the gambling part , i am just torn by the fact that she never told me this. I had asked her 100 times about their family background but she lied by omission.

I feel like she should have at least told me, i would have covered for it at home. It was very humiliating how i had to learn this info from someone else.

My parents are convinced that i am a retarded fool who can easily be manipulated by a girl but i really love this girl, she says she didn't tell me this because its not about her and also that she was embarrassed. She said they stopped but i got her to reveal that the father might still be involved in it at a smaller scale.

It led to a huge fight, i was mean to her and compared her lying to my ex's lying but i never demeaned her or her family for gambling. I am now blocked by her

But in my opinion, this is something you should disclose to your future husband if you are seriously going to marry them right? Am i wrong in this assumption?

Am i over reacting ? What should i do next? I really love this girl

TLDR: GF didn't tell me about her family background of gambling and we even had family meetings, we had to learn this info from another person