This is more to rant than seek advice, but happy to hear any input too.

I have a complicated relationship with my most recent ex. To put it simply, he meant a lot to me and I meant very little to him. We eventually broke up because he was unsure he wanted to label it but really wanted to keep seeing me. The final straw came when it turned out he hadn't even told most of his friends we were dating. Friends that we'd hung out with together. We also work together and was uncomfortable with people at work knowing. The work thing hadn't raised red flags as it seemed fair enough - our co-workers didn't need to know our business and my work friends knew. I assumed his did too.

Eventually we broke up - horribly to be honest. It was in public and essentially because his friend saw us together. Turns out he'd tried to break up with me twice before but he'd been so indirect I hadn't noticed and he was to cowardly to clarify. One of these "attempts" was a Christmas card that ended with his first "I love you" so you can understand my confusion.

Queue a few weeks of him trying to immediately be my best friend which seems to have been what he wanted all along. I declined. Asked him to stop reaching out, avoid me in work (our actually jobs rarely overlap). Eventually he did and I kind of got over it. I would still never plan to be around him or spend time with him but was happy to be with him at after-work drinks or the party of a mutual friend etc.

He called me into his office one day to tell me he has a girlfriend. At the time I thought he was being kind, didn't want me to hear it from others. Now I think he was just trying to rub it in. He'd been long term single before me and claimed to be happier that way whereas I would really like a relationship. He'd been coming to an event I organise regularly and wanted to bring her too. I said absolutely not. For one, no one else brings partners or friends. It's just not that kind of thing. But mostly it would be so unpleasant for me to sit there and watch him with his new girlfriend who is apparently not an embarrassment in the way I was.

Anyway, fast forward a month or so and he'd been really rude to me and several friends of mine since then but today was very nice and helpful to me. I thought we'd turned a corner. We were just two polite colleagues getting on. Then when I get home he's sent me a message to say he girlfriend was coming to my event tomorrow and he's sure it's not an issue since we're friends "again" now. I told him that she's not invited but he didn't reply.

I'm just honestly floored. He has such a reputation for being a genuine, lovely guy in work. And it kills me that he gets away with being such a manipulative prick. I've gone on 9 first dates since we broke up - one turned into a few weeks of dating but that's it. And this scumbag picks up a beautiful, interesting girlfriend within a month. I'm just so angry. And how naive was I to think he was just being friendly????