Ya gotta not be so helpless. You can't be the type of person who is still, after five months, pining for this girl who has clearly moved on if you want girls (including this one) to be attracted to you. This girl isn't that special. There are literally billions of girls in the world, and millions right in your own state. Think about her all you want, like you think about any good memories. But stop wallowing. She's just an ex girlfriend. I have a bunch and most of them mean a lot to me. They represent important periods of my life and I was madly in love with most of them.
But, ---steaming pile of meadow muffin---, none of them compare to my wife. And I'd havenever found her if I was all broken up and crying about wanting to be back with some other girl. I don't know how long this relationship was. The longer it was and the bigger a part of your daily life she had become, the bigger the hole her absence will leave in you. But you just gotta fill it up with other ---steaming pile of meadow muffin--- -- and not stupid I-kinda-feel-like-being-alone kind of ---steaming pile of meadow muffin---. Just live your life. There's something absurd and maybe megalomaniacal about behaving as though there is this one special person in this world who is perfect for you. She aint that special. If there did happen to be that ONE person, the chances of the two of you happening to meet are infintessimally small.
In short, man up. It's been five months and it's not like you have kids with this girl. It's time to move on.