How can I make up with my exBFF?

Me and my bestfriend(kara) have been best friend for almost 5 years. On 2005, My bestfriend started to act funny around me and etc... I got upset cuz I asked her what was wrong or did i do something wrong and she was no(contantly lying). So next day, My other BFF(Chris) told that she talked behind my back and etc...I got extremely hurt and pissed! I told her to meet me at star buck coffee to solve this problem as adults way. But she wasn't being mature at all cuz she wouldn't tell me, But I already found out. She even got my mom, her mom and other BFF's mom involved this BS. I decided to forget her the for while cuz it was really stressed me out. I took a nap and mom woked me up to tell me what just happened. BBF's mom call my mom to see if everything was ok and she said that she noticed that kara trying to make me and BFF apart. I realized that she was jealous of our friendship, I don't know why, I was her BBF too. So I decided to drop it and try it again but a week and half later, all of sudden, she started to flirted wit me and wanted to have with me.(crazy, huh) I couldn't help cuz TOO much **** been going lately, so i told her to meet me at starbuck coffee again the next day. As soon as I talked to her abt the past and etc.... She gave this attitude and I had enough, So I talked (bleep) out of her. It was out of control and she kept apologized and whatever. I didn't care cuz she wasn't a real friend to me. She was pregnant that day and I had no clue. She is only 20 yrs old and he is 30 yrs old man.(geez, that's messed up) She changed alot after that. Now she got mad at me cuz she said I revenge on her. I never thought that, I did that cuz I was hurt and didn't care at all. Havent seen her since I was visit my high school performance on april 2008. Now I might see her at the big party. I was like kind of nervous abt it and it will be so awkward to see her there and might bring her baby there this sunday. Ofc, I did forgive her and I kinda miss her a bit. But how am I going to do this? Go up to her and said hey how r u? or what? Any advice????