I'm going through the same thing it's hard and I understand it's not easy to leave someone you put so much effort into when it comes to love... I won't tell you to let go... Hun fight for your life... I did and I got him. And if he really only LIkES this girl then he would never leave you for her. So take one deep breath and take a good look in the mirror, tell yourself your strong... Then ask your self. Is this one guy worth it all? If it's a yes then go for it and never give in. If you need help with anything my aim screen name is miss35775 I may be 13 but I have gone through more things in life then most adults my step mom even said so. So good luck!
