Tips to be my best self?

Okay so tonight I am going out drinking with my boyfriend and his friends from work. A few weeks ago he cheated on me and kissed a girl from work. We moved past it and everything but some people he works with know about it.

Tonight will be my first time seeing them since it all happened. Im a very shy and socially anxious person and im worrying about how they view me now.

I just want to come across as best I can and if anyone thinks badly of me prove them wrong. Also in case the girl is there I want to show her we are strong and she wont get in the way.

Im not sure what to wear as I want to obviously look amazing but also dont want to look like im trying too hard? And also because I am shy I just want to come across well so if anyone has any tips for faking confidence and being friendly?