How to break up?

I have known for a while now that my girlfriend is very manipulative and is taking over my life. She made me stop being friends with many people because it makes her uncomfortable yet she continues to act flirtatiously towards others.

I’ve posted about her multiple times and everyone who commented has told me she is acting manipulative and immature and that I should break up with her. I don’t know how to suddenly break up with her and I would like to be nice about it as she is still a nice person but very very manipulative.

I’m scared to break up with her because all my friends are her friends, and they would definitely take her side. She introduced me to them and she would definitely twist the story to make me seem like the bad person.

I don’t want to lose her as a friend or lose the other friends I made through her but she is taking over my life and i’m willing to lose the friendship I have with her as I feel like she intentionally tries to make me jealous and worried about our relationship and i’ve had enough.

Should I wait for something to happen so I can break up with her? Or just suddenly break up with her out of the blue. Yesterday she messaged me saying how she didn’t want me to leave her and if I did she would lose everything and she didn’t know what she would do. I don’t want her to do anything bad to herself, however I really feel trapped in this relationship and I know it is very toxic.

I don’t know what to do