ok. to put it short in the beginning, my girlfriend willingly hangs around men alone that want to fuck her, and she knows this

ive never had a problem with my significant other having guy friends. i knew she had tons of guy friends in the beginning, and it was no problem to me. stuff started coming to the surface. i found out she’s slept with one of them 3 times and the last time was a month before me and her slept together, and things became serious between us. so it made me upset. it was kept from me, and it hurt that she could so comfortably look this man in the eyes every single day, then look me in the eyes and tell me she loves me. she wants him and every other guy around because they’ve all been friends since kids. after a recent argument she exposed out of emotion that they all want to fuck her, that they like her, etc. but she only says in defense when i bring up how uncomfortable it makes me “i’m not a cheater”. she has about 4 female friends out of 56 (exaggerated) male friends. and that reason being is because of some high school drama that happened. all she says to me is i need to grow up and get over it, and she doesn’t care that it affects me deeply. i just don’t want my girlfriend hanging around a group of guys that all want to fuck her, especially one on one hangouts when she even knows that’s what they’re thinking and want. someone please give me advice, tell me im bugging out about it, or agree that it’s not morally correct. give me something. im losing my mind