You nailed it. The entire family were atrocious hosts.

That’s what stuck out for me, not only did BF leave her alone for the inquisition, he started picking on OP. If he behaved that differently around his family the FIRST TIME be brought her around, his ‘good behavior’ when not around them is a lie. That’s who he is for real, he showed her and she should believe him. You deserve better, OP, and leaving that toxic environment was a good first move for your self preservation. Take care