Judging by what I read she’s confused and she’s also testing you. To put an end to this confusion you may want to consider what role you want this woman to play in your life, and just clearly establish that with her. She clearly wants you to be into her but is frustrated that you aren’t fully invested which you probably shouldn’t be since she left before, despite what her reasons were.
She left you so there shouldn’t be a reason for you apologizing for dealing with other women in the first place. It would be different if you told her one thing and did something different but according to this post, you already made it clear that you’re openly dating and encouraged her to do the same. I see boundaries that need establishing here.