Advice please!! Feeling insecure

I recently found out that my boyfriend was talking to another girl. I got really upset but I wanted to clarify things. So I asked him about it... he just told me that they were friends but he knew she wanted more. I still don’t like the idea that my boyfriend is talking to a girl who likes him and flirts with him. I mean, who does?? I told him to drop their friendship and he said he will, that’s all he said. Yesterday I asked him again if he talked to that girl about it and he said he started it... I’m so confused and I don’t know what to say to him anymore. I don’t want him to catch feelings for that girl or whatever. And it bothers me so much. I don’t even know how to bring this subject up again or if it’s a good idea to. Ladies, I don’t know what to do honestly 😔