I will see my crush after seven month tomorrow?

I have became friends with this girl in grade 11 and we became closer in grade 12...We use to joke a lot with each other. Last year we finished high School and she moved on after hat...After we graduated I started to miss her so much, I discovered that she meant for me more than a friend... I think its matual, but I am not 100 percent sure...One time my friend commented on facebook on a photo of me and her saying that we suit each other and she replied "LOL (-my name-) is my cousin" as in best friend she meant and after that she became shy infront of me. I havn't talked to her in like 7 month. Tomorrow I will be at my friends birthday party at a restuarant and she will also be there with another 12 people.. I am excited about it but also worried that something might go wrong. Usually me and my guy friends joke and tease each other in a rude way. So its ganna be awkward infront of her if someone said something stupid about me. Also I dont know how I should behave, should I talk much?? And should I act funny or serious or maybe tease her by saying that her friend is looking better than her. Idk I'm scared of freaking her out.