Help a girl out

My boyfriend asked me if it was okay for him to go to a party with 3 of his friends and a girl I don’t like and her friends (just them at the party)

I’ve never met her but I don’t like her because she popped up on his Snapchat for a few months and they talked a lot and now apparently they don’t talk to each other.

I don’t want to tell him what he can and can’t do but it’ll make me uncomfortable if he goes and he always talks about how his ex was controlling and I don’t want to be like that.

And if I say no he’s gonna think I don’t trust him but if I say go I’ll be upset. What do I do?

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Thank you for your comments. I told him how I felt and we got in a little argument Bc he thinks I don’t trust him. I explained why I didn’t like the girl and he said he understood. He told me I could come but I idk if I’m going to.