Once I can see, but if she's making a habit of this(and with your FRIENDS too)why would you want this girl? Please, Walo, getting a girlfriend just to forget the other isn't right, & will really hurt the 2nd girlfriend if she finds out that she was just a replacement. Hang loose, wait til you find a girl that you REALLY like, don't just settle for replacement parts!
You should have ended the relationship after the first infidelity, but end it now. The worst thing you could do is jump (or rebound) into another relationship. Bad for you and the other person. Give yourself some time to heal...at least 6 months. Focus on yourself, school, work and improve those aspects of your life, after all, they've probably taken a back seat while all this was going on.
Well...do what i did. do you have some friend that is willing to go with you, confront your girlfriend and your friend, and cuss them out, diss them out with good points, etc., then you'll leave the scene laughing hysterically and then not only will you feel better, but you won't have to deal with a bad friend/girlfriend. It really does help. Except for me, the said friend that helped me out was a somewhat new friend i made, and he only helped me out cuz he knew how i felt.