Run in with girl from high school

Just recently I saw this girl I used to go to high school with in my apt. She knows my one roommates Derrick. She has a 3 yr old daughter and hasn't changed much since high school, just gained weight from her pregnancy. I was never friends with her but we both used to date this one same guy we both knew{different times of course}.Anyway she was also with Derrick's x-girlfriend and mother of his son{Karen} and Anthon. He's only 2 yrs old. They went to go get some stuff and came back and we grilled some food outside. So it was me, Derrick,Anthon,Anthon's mom{Karen}, the girl{Jamie} , her daughter{Katie},Chad and Jason{lives below me}. Karen is talking about having a picnic on saturday so maybe I'll go. Something to do.