I play exactly what is in Version 2 of the Irreplaceable chords
(http://www.ultimate-guitar.com/tabs/b/beyonce_knowles/irreplaceable_ver2_crd.htm.)
but I think this might make a better bridge:  

Capo 3



Em                     D
So since I'm not your everything

               Cadd9
How about I be nothing

G                 Em
nothing at all to you?

                    A
Baby I won't shed a tear for you

C
I won't lose a wink of sleep 

D                    
cuz the truth of the matter is

Cadd9            Em G
replacing you is so easy...



The rest of the song is just repetitions of G, D, A, C as shown in Version 2.