Am I tripping?

I am a 25F and my girlfriend is 22F. We have been together for about two years almost. Since day one, I have always said and told her I do not feel comfortable with my girlfriend hanging with a guy alone. I wouldn’t mind if it was a friend group thing and they all were just hanging out together but just him and her alone is no for me. So this boundary is nothing new. However, she has this gay male friend that she met about a year ago and she continues to hang out with him alone, at his house, at work. Mind you this “gay” guy has slept with a woman while also being in a committed relationship with a guy. I don’t trust him at all. But she continues to say “I have nothing to worry about” “I only want you & no one else”

My girlfriend thinks I’m trying to be controlling but I’m genuinely not. I’m just not comfortable with her being with this guy alone but yet she continues to do it regardless to how I feel and expects me to just be ok with it. I keep telling her over and over again that am not ok with it. but it’s like she doesn’t respect my emotions. I have cut people off that I was close friends with because she felt like they an issue. I cut them off with no issue but now that it is reversed and I’m uncomfortable it’s a problem. Mind you, you, we are both women. What do you all suggest I do about this?