First time poster, long time lurker and know you lovely lot will give me the best advice.
Background info...early 20s, was sexually abused when I was 16 by partner 5 years older, went on to be in an awful emotionally abusive relationship until the back end of last year. (This is relevant I think). This series of events happened at the start of this year.
We will call the man in question john. He's a manager where I work and is 10 years older than me. He has a partner whose job he moved to the city I live in for. Not my line manager but have equal contact with all managers as I work in the main office, got a promotion to do so at start of year.
The situation started with just flirty banter. I thought this was just how he was until he moved the convo onto social media. We got on really really well and became close, he confided in me about his relationship issues (lack of sex life etc 
) and I confided in him back, I related to what he was saying because my recent ex refused to touch, kiss or cuddle me as part of his abuse but I went on to confide in him about the rape. I was suffering from PTSD, anxiety and depression at the time and had just started medication. I told him this and all about my past relationships and how awful they'd been. He would message continuously and started using pet names, messaging me inside and outside of work and became the person I was closest to at work. He would mention considering leaving his partner and talk about how unhappy he was. It ended up him asking me to meet him after work to go for a walk, the crap weather meant he ended up coming to my house. He picked me up from a car park near work (but out of eye shot of it) and came over, I put a movie on. He started trying to do stuff but I was still really uncertain due to his partner. He wanted to have sex but I said no but stupidly felt like I owed him something since he was at my house so did stuff to him. I felt like he wouldn't feel as guilty if he hadn't done anything to me. I really cared for him at this point.
He then was really off with me for a couple of weeks, then would have a good convo then go back to being off with me. I was really deflated as felt I had lost a really good friend who I had confided in (didn't really have anyone else, ex didn't really allow me to see any friends so it dropped off with them). A few weeks passed and he messaged me asking me to go over. Had to get snuck in the back. He wanted me to have alcohol but I just had a water and sat awkwardly on sofa. He tried to initiate things but I was still really unsure so he leaned over so his back was on my chest and his arm was over me so I couldn't move and I said something along the lines of you've got me pinned down and he said 'that's the point'. I thought it was just his kind of thing. Anyways he was trying to hint at me doing stuff to him and I now felt obliged since I was in his house and he had done stuff to me. I was timid but he ended up going on and on about full blown sex, keep repeating 'sit on it just sit on it man'. During this I got a message to say my ex had called the police on me saying I was harassing him at his house which shows how the manipulation was continuing. So anyways I did what he said stupidly and left not long after. He barely spoke to me in the weeks after and now speaks to me like muck over trivial things which I call him out on.
Fast forward to now. I'm in the best relationship with the most amazing man, can't believe how lucky I am. He's wonderful, and apart from the main things doesn't know much about my past with men and doesn't really want to, as he says he loves me for me now and nothing in the past really matters (apart from the main things affecting me now obvs). He's great. However a rumour has started at work that I'm seeing john, somethings happened with us and I'm on the sick because of him along with lots of other added details which aren't true. I'm off on holiday so can't even set the record straight so hoping it blows over.
However...A girl at work a few years older than me heard what was being said and has got in touch with me to say something similar happened with her and john when she was my age. He was her line manager at the time and she was, similarly to me, suffering from PTSD and other mental health issues and was in a really bad relationship. He would take her to the pub at the top of his street and have drinks with her until she was a bit 'too' drunk and take her back to his house, ended up having sex with her, being quite forceful with his language and actions and had done the same in terms of getting her to confide in him.
I now don't know what to do. The girl says she will also come forward if I went forwards but she's pregnant, so could probably do without the stress, but then there's the worry of if he's doing this to any other girls. Add in the feeling of guilt (we both know we're not innocent in the situation) and we are at a loss of what to do. CPS have also just come back with rape charges against my first ex so have that to deal with. Just need someone to talk some sense into me please !! I think my view on things is warped because of my past and I've downplayed situations which are bad.
Any advice welcome 