look, you are OK. don't let the fact that he is with another girl make you feel unworthy! i've been there, done that! and not for a few months, but years, long years!
i'm still asking myself why i didn't fall in love with the guy who was perfect and did all the things i liked but with the one who just messed my life?
the truth is, there are people who will always like/love you just the way you are. and there are also people who won't like/love you no matter what you do!