How could she be so spiteful?

Anonymous
Me and my boyfriend have been long distance for 9 months due to work. We were together for a year and had a very good relationship and serious. After 4 months of being apart i visited him and everything was fine. 2 weeks after i went home i saw a girl liking all his pics so i messaged her and asked her to stop. I confronted my boyf and he said that he saw her in the disco , she messaged him and they danced together but that was all and we left it there. 5 months later i messaged her as i became very anxious and she said that they slept together in January. I confronted him and he said it was all lies and that she was a jealous girl. He became very angry too. He would deny it profusely. after 2 months of my boyf denying it with force i texted her to see what happened. She sent an audio message saying she slept with him in January and i sent it to him and he denied it all again. A month later i texted her asking why she lied and she changed her story and said that they actuslly slept together every Saturday for a month. He became more angry and told me that she was a jealous crazy girl. I thought it was strange how she changes her story also. I asked her what hotel she went too and the hotel she named wasn't actually open when she claimed to be there. The hotel did not exist. After 6 months of asking my partner if he did it , he still denies it profusely everyday and even when i told his sister he said he didn't mind as it was all lies. . I texted her in a nice way and confronted her about changing her story and the fact that the hotel was closed and she called me all kinds of names and sent me voice messages saying that there were things wrong with my head and kept trying to call me and then blocked me but never explained herself. How could she lie and be so evil?
How could she be so spiteful?
2 Opinion