being accused for rape,England

I had sex with my partner's friend twice. She invited us to her house for a party and we stayed with her for a few hours alone. After that she wrote me messages saying she wanted to be with me and that she got pregnant from me and lost the pregnancy very quick (without any proof from the doctor). Now she accused me of raping her and i have been arrested. I had sex with her a year ago, and she filed a complaint with the police after 5 months, that I grabbed her by the throat etc which is not true. I have her messages as proof where she wrote to me that she wants to be with me etc. and to leave my current partner. My partner works with her boyfriend and she comes to work place and accuses my partner of having sex with her boyfriend.Everyone thinks that this was a plan organized by her to get revenge on my partner and I was lied to and put in this situation, My acyual girlfriend and this woman have been fighting for about 2 years( they worked together and her boyfriend still works with my actual girlfriend, there are messages that show how they fight and how this woman said her that she will ruin my girlfriend life. Can you please advice how to proceed,i am in a big stress ? Thank you