Help a sister out would ya

I am lesbian and I had a girlfriend for almost 4 months, then things started falling apart. She was too busy to talk to me and I ended up catching feelings for two other girls... they are both straight. I told my girlfriend and she ignored me for a month and a half and I can’t do this anymore, she’s still ignoring me and I don’t know what to do. I don’t want to break her heart but she already broke mine. Any and all help is accepted, does anyone have ideas on how to break up with her?