Relationship problem :(?

K so I have been going out with this girl for 5 months now and before I started going out with her she told me how she has had sex with 4 other guys before and I was okay with it but now I think of it like **** another guy has been inside her and it feels gross to me and I'm not sure if I want her in my future so any suggestions will be really helpfull and please if you can't answer it jus move to the next one instead of writing hating comments so should I stay with her or what? Because there is no way she will be able to forget her first so its like there's always gonna be a guy other than me that she can never forget :/ sigh