Last year I had a fwb relationship with somebody at work ( I have posted about this before) it then turned out he had a girlfriend who had recently had a baby. It also turned out he is always cheating on his GF. To give a bit of background, when he started messaging me I was on sick leave having had a major operation and I was basically housebound. Prior to his message I had only spoken to him about 5 times, just general banter, no flirting. I would not even have classed us as friends. It seems he started messaging when he noticed I was off work and found out the situation I was in. We were messaging for 4 months before anything happened with him always contacting me first. It didn't end great as after it all finished he admitted he had been with his gf for some of the time I was involved with him but I believe he was with her the whole time. It has taken a lot of time and conversations with people to realise it was very emotionally abusive, gaslighting was involved and now a couple of people have said he took advantage and was able to manipulate me because of my situation at the time. To make things worse just after he admitted about his gf he told me she was working for the company, it was somewhere I was unlikely to come across her but that also turned out to be a lie as it was somewhere I probably was going to come across her and I did. I have been suffering with depression for several months over this and cannot go into certain parts of the business for fear of coming face to face with him. Friends have said I should put in a complaint as he took advantage of a vulnerable colleague. I don't know whether to do this or even if I would have a leg to stand on. Just to add, nobody can make me feel more stupid than I already do but I really don't think until you have been with somebody who is so manipulative you can understand how clever they are at drawing you in.