Would you girls ask another girl if your ex cheat on you?

ok, so This been bothering me for days..When i was with my ex one time i saw this girl texting him with hearts and kisses..He said it was a friend, i was really blind that i decided not to make a big deal of it...we broke up but i felt guilty for things that i didn't do he made it seem that i was the one who fucked up the relationship..i don't want to feel this way anymore is eating me inside..I know the girls name and i know her facebook page. would you girls ask her if they had something while he was with me? i know for sure they don't talk anymore..but i don't know i felt this way i would say finally to myself that he wasn't the person that i thought he was..i really want to know...Help!