My ex got with his ex girlfriend a week after we broke up? How can I get him back?

[Whitney]

If you honestly even want him back after most likely sleeping with that ex you were so insecure about...I would talk to him in person and just lay everything on the table, be like "listen I know we both made some mistakes these past few days, but I really love you and care about you. Is there anyway we can make this work?" if he is willing to work things out then you both are going to have to work on those insecurities and everytime you get into a fight you can't be running to that one guy that gets under his skin lol and if you have a problem with this girl......honestly f*ck that b*tch she slept wiht your man....I would just tell her straight up that you don't want her around!!! Seriously!! She is causing so many issues with your relatinship! why does she even hang out with you guys still!!