Is it normal to feel bad because my girlfriend [19F] told me [19M] about how she got her tits sucked by her ex?

Actually we both were talking about us having sex and us having intimate things because all we did was kissed at that point and thought I'll save our virginity but while talking she opened up suddenly that she got her tits sucked by her ex, I mean the crazy part is before coming into relationship she told me she only held hands with a guy nothing else but later on she kept on dropping me bombs after bombs so it was actually after 6-7 months of dating and she told me that then I was so angry and sad that I already had sex with her multiple times and took her virginity but still this comes into my mind again and again...