Seen my x-girlfriend tonight and she acted like she didnt see me at all?

well she recently told me she was gay now but apparently i saw her with 3 other dudes tonight on the party strip. so she SEEN mel, kept walking. why would she do that. i got madd and threw something at her and the dudes were ready to confront me after it but i didnt care about them at all i was offended that she acted like she didnt see me. so i dont get it. ???maybe cause she didnt want them to feel awkward but that girl has got serious issues to think i even was interested in her at one point in time! shes too insecure and inhibited i cant deal with that thing no more, especially she showed her true colors on that one. does anybody here have any input as to why she acted like this tongiht? odd behavior or normal?! im an observer if you would and i am trying to read her well, still somewhat baffled, but please give me possibilities as to why she would do that. thankssss!