Relationship advice needed...

So my boyfriend of almost one year broke up with me two months ago. He got back together with me a couple of days later and then after a week decided to end it again because he “didn’t want to mess me around” is how he phrased it. Throughout majority of our relationship, he was getting close as “friends” with a girl at his work despite me telling him she obviously liked him. Lone behold the day he announces the break up she confesses her feelings for him, obviously this is crushing for me. Since the “break up” we’ve still been hanging out and going out and staying round each others houses, still having sex and everything, nothing has changed there is just no official title. All the while this girl thinks we hardly speak and that I’m a psycho ex which is why all his friends are being odd because apparently that’s what he told them “to make it easier for him”. So he wants this girl but he also wants me or so he says, he’ll hang up on me to talk to her but we still have holidays booked for a few months time. This girl messages me trying yo be my friend, denying her feelings for him despite her having told him and me being shown the messages. He could get away with murder and he knows that because o’m so hopelessly in love with him and he turned quite manipulative. I feel like i’m in a competition 24/7 but he says he doesn’t know for sure what he wants and i’m not ready to give up on what we have.

WHAT DO I DOOOO!!

any help and advice is much appreciated because I honestly feel like i’m going insane xx