Feeling left out

I guess feeling left out is normal. The closest friends I've ever made was in college where we promised each other that we'll stay close together regardless if we get married and have kids we'll find time to hang out with each other. 2 years of college our bonds grew stronger and we get into the university stage. Although we got separated; 2 share the same uni in the country, another 2 flew off and the rest of us (including me) attend another uni in the country. For us who still stay in the country we still met each other usually having lunch together while we sometime Skype with the other 2 who were out of the country. Then we met another girl who seems interested to befriend us. We pity this girl because she seems lonely and we heard that most people don't like her so we said to ourselves 'why not WE try to accept her?' But as time flew the girl gets more comfortable to show her true colors and let's just say we don't like it too. My friends then reali