girl im talking to is “friends” with all her ex’s

so there is the girl im talking to (19f) lets call her cassie. so me (19m) and cassie have been texting since late may but got serious like a lil over a month ago. she admitted to me that before getting serious that she was still in contact with her ex but that she cut it off as soon as she realized she wanted to make what we have serious. she has told me very little about her past ex’s which i dont mind too much but she did talk about how she’s still friends with an ex from freshman year of hs which i dont care bc we were literal kids as freshman. but recently a couple days ago she had told me that her and recent ex have no bad blood anymore and that they agreed to being friends. keep in mind this is her most recent ex and he cheated on her so all i can think is that’s weird and why would you want to be friends with a dude who cheated on you. they used to coparent a pet together and she recently say the pet and i was so confused when she had told me bc she did not mention that in her things to do for the day and that means she went to her ex’s house. i voiced that it made me uncomfortable that they’re friends last night and the conversation didn’t go to well she basically told me that she’s cool with all her ex’s and talks to them every now and then and just said that a neutral relationship that her and her recent ex have shouldn’t effect what me and her have , but…. it does lol. im thinking maybe i didn’t express myself well enough last night bc it was late and i hate being confrontational, plus i feel like i shouldn’t have to be worried about something like this. especially bc i voiced that it makes me uncomfortable. i’ve really grown to like this girl so much and it’s really hard for me to just up and leave but it’s looking like that’s my only option.

TDLR: girl im talking to is “friends” with her ex’s but being friends with her most recent makes me uncomfortable considering it ended so recently and he cheated on her