If Rachel had been killed instead of Tom , would Anna've called the police?

[Fourth]

I finished the book yesterday and couldn't seem to get this out of my mind: Anna had so many chances to call the police, but she didn't until the very end, which is after Tom had been killed. So it makes me wonder: does this mean that Anna doesn't really care if Tom killed Rachel? (at one point Anna said; ''He hasn't finished it [killing Rachel]. I'm not sure what he's waiting for. I suppose it's not easy for him. He did love her, once" And if Rachel had been killed instead, would Anna still cover for Tom and act like nothing has happened, and still stay with him?Paula Hawkins