Advice? friend done me wrong.?

my best friend whove i nown for 13 years has upset me, i do get alot male attention but theres this guy who told me he liked me but is a bit of a womanizer. my friend give him her number and startin flirting. she likes sum1 but hasnt got with him yet, i was really pissed of with her. she knew i was meetin him. am i over reacting :S xxx