I can't get over her and want to be with her?

I talked to this girl for 4 months. We stopped talking cause we wanted different things at the moment. We didn't speak to each other for a whole month but recently we contacted each other via text and expressed how we missed each other. Because of that I invited her to a party...after inviting her I learned that she was with a guy the night before and was making out with him. This made me angry and I felt played so I told her that she could still come to the party if she wants to but not as my date. Anyways, she still came to the party and we ended up talking the whole night without bringing it up. The only thing I asked was if she was seeing this guy and she said no. I'm over the mind games. I either want her to be with me or want her to tell me she doesn't want to be with me so I can move on. Leaving the possibility of being with each other just hanging out there is keeping me from getting over her. What should I do? I'm having a get together for my bday next week and I am going to invite her. Should I tell her exactly what I want and that she needs to decide instead of leading me on? And if she doesn't come, should I just text her and tell her what I feel?