Stabbed in back????

ok just found out that my "best friend" is going on holiday with the girl i fell in love with a while ago, (who i broke up with as i knew she was never intrested in anything serious) anyone else think this is stabbing me in the back? i know i should just get over her but it aint that easy especially as he was always slagging her off, now shes got a new look and is looking sexier than ever hes suddenly intrested.