Boundary Question Part 2

I read your response about the situation with my dad and his girlfriend. Your feedback is that the boundary is with the girlfriend and not my father.

I understand that and it makes sense.

I also feel there is still a separate boundary between me and my dad to create.

Otherwise he is condoning her behavior. And really – contributing to it. He tells her words about my life, she forms many negative opinions about them, and then days/months later says inappropriate things to me based on having that knowledge. He never acknowledges those behaviors or things she is saying to me (that is why I mentioned sending him the screenshot of the text or email) and the cycle continues.

Yes, of course I want him to “stand up to her” but I know that is not going to happen, so in an effort to love and support myself through this, I feel a boundary with my father is needed too.

What am I missing here? How could I develop a healthy boundary around my father and the behavior he keeps condoning?