My girlfriend is killing me!!! She talks about exes and past experiences... And I keep finding out more!!!?

So anyways me and my girlfriend have been dating for 4 months now and at first i was like ok, maybe its just one of those things... she wants to talk about our lives... but its been 4 months and she still talks about other guys shes banged and im like wow!!!! I dont wanna hear how u bang all these guys before me. Oh and I always find out that their is always another guy... Like they just keep adding up... Like seriously ive counted 12 guys... since we've been going out... she said they were over a 12 month span! Oh and she constantly talks about her exes... Like kevin did this and johnathan did this! Does she really think i want to hear about her dumb as exes? Seriously? Am i being to rash or am i normal to feel this way?