Friends of Yours

Several friends of my wife are going to come to our house this weekend. It's kinda fun, because there might be a lot of food left.
The good thing is that I know her friends who are going to come. But it just makes me think what am I going to do if the next gathering consists of people that I am not close with, such as the colleagues, the former classmates, the in-laws?

I mean, her group is not used to have me around, which would naturally cause them to talk not as free as they used to. I am also not really comfortable being a new guy in that group.
It's worse when the group consists of the opposite sex. Then it will be impossible for me to join her group and her to join mine. The conversation topics will just not match. The girls will only talk about trivial things like who's dating whom and how to make the best cake. The guys, on the other hand, will talk about profound global issues, such as how Liverpool beats Manchester United, or the latest Playstation2 games.

So now the question is what should I do when there's a gathering involving all of her ladies friends that I don't know? It was not even a question before we get married, as I could just do what all men do, stay at home and pretend to be sick.
But now that I am married, my home is also her home and that means I can no longer use the excuse. And as the house is very small, I cannot stay in other room.
I guess I need to start learning how to make a cake.