Do you think she was using me in some way?

To be honest I think she was plain out using you, maybe didn't even like you that much and hence that was whys she didn't kiss you or anything. She sounds like a little *** and I don't think you should be wasting your time worrying about her :/ it seems like she was trying to get back at her ex but it also seems like she still liked him and so she used you to get him jealous and perhaps want her back. Forget her and try to move on, she won't be worth it at the end of the day if she behaved like this