From what I understand and from some articles written, this counseling is pretty accurate, especially for a TV show.

The dynamics of these scenes are how counseling an abusive pairing usually goes. Celeste telling the counselor about the abuse could get her in trouble so she isn't forthcoming. Perry IS forthcoming....but only to a certain point. By admitting it turned physical, he gets to decide how much he abuses her and the degree to which it's dangerous. And he tries to manipulate the session by talking about his insecurity that Celeste will leave him. Celeste feels the need to make him feel better. Lesser therapists can get sucked in which is why couples therapy isn't recommended for couples in abusive relationships.

Celeste stays because she's been conditioned to care for Perry and he gaslights her into believing she's partially responsible for the abuse--that she secretly likes it.

The therapy scenes and abuse storyline are the most compelling, IMO.