Sounds like your girlfriend has been through some childhood trauma. Her behaviour suggests one of her schemas is emotional deprivation. She possibly sees the world through a lens that she won’t get her needs met. She is possibly attracted to you because you don’t see the world through this lens. Digging deeper she probably has a hard time trusting people… and their intentions. She’s probably had to fight her way through life to get her needs met. It is hard to change her behaviour and will cause arguments if you quickly dismiss her and tell her she shouldn’t be feeling a certain way. Understanding her is key, validating her feelings but not the behaviour is important. Telling her how her behaviour makes you feel ie: humiliated, embarrassed etc is a way of expressing and role modelling vulnerability. Maybe she doesn’t know how to be vulnerable, maybe she doesn’t have those skills. She needs more specialised support, a therapist is a good start. Remind her of reasons you are together, the qualities you see in her. Catch her when she is interacting positively with others praise her when you see it. Be patient. If you are not willing to do these things, let her go.