What should i do about this girl? (10 points best!!!)?

It was obvious if If I ever saw it she is trying to make you jealous. She still really likes you she just doesn't know how to tell you. You obviously notice when she's making out with him, it is also her way of seeing what kind of guy you are, if you would get jealous of her around other guys. Trust me the minute you come out with your feelings, that other guy is probably history. Go after her, she wouldn't go to all the effort, of putting her and this guys relationship in front you , if she wasn't trying to tell you something. Spilling your feelings is anything but easy , but the next time you have the moment don't think about just do it. Out with it. Good Luck.