Is this why she hates me?

So im seeing a guy in my job at the moment. We are officially boyfriend and girlfriend but before we got together and before I came to the job he used to drukenly kiss another woman at social events. They never spoke or hung out but they would drunk kiss eachother at social events and a month before me and my boyfriend started dating she asked him to go away with him to a hotel. He also touched her sexually a few years back too. He has no feelings for her whatsoever and never did. But in the past year since me and my boyfriend started going out this woman has started giving me really dirty looks , talking about me behind my back and spreading false rumours about me. She also started on me one night and accused me of talking about her even though I didn't. My boyfriend has not spoken to her in over a year but she is still behaving like this towards me. Is this why she hates me and is behaving nasty towards me? Its strange because they only ever had drunken hook ups and never had sex.

Is this why she hates me?
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