Been talking to her for a couple months, but I don't know what to do?

So I've been talking to this girl for a few months now and I like her. She invited me to be her plus one for her sister's birthday yesterday, so I'm assuming she likes me back as well (although I'm unsure and too scared to ask). Then I came across a few photos on her instagram with her ex in some intimate moments. Like I know that guy was part of your life, and I've had my own fair share of relationships in the past, but I don't necessarily keep them in my life if that relationship is out of my life. She has told me about her ex and how he was kind of a conniving bitch. So I don't understand, if that guy traumatized you, why would you keep him on your Instagram. Should I confront her? But I also feel since we haven't really started dating I'm in no position to talk about this at all.

Also, as far as I can say from her posts and her behaviour, they broke up several times during their relationship, but I think the final straw was in Feb of this year. But even after that they attended a concert together maybe cause they part of the same friend group. Meanwhile I've been talking to her since December, so again I don't know if this is making sense at all. It's all I've been thinking about since last night when she asked me and then I found all this out.