<human>: Could you distill the essence of the text into 1-3 sentences?

So I'm not sure if this is the right place to post although it is regarding my ex. I don't really care for the situation with my ex anymore; he basically started dating someone while leading me on. My main question is whether I have done anything unreasonable. Basically we were supposed to meet up in a group before we fell out but after finding out he was seeing someone yet he still had arrangements to meet up with me I got pissed off and had an argument with him though all online.

Now that's over so I don't want any opinions about it. However I forewarned a mutual friend about him maybe not turning up due to our falling out. I had to continue staying in contact by text to see if he was still attending or not and he told me I shouldn't have told anyone about his relationship with this girl because it's "unofficial". Now I don't know many details about him and his new date apart from he has gone out with her a few times and he likes her. Yet he says it's rude of me to tell others. 

In my defence he never explicitly said I couldn't tell anyone else. But he said it goes without saying. I'm just asking you guys because I'm not well versed in unwritten social rules and I did tell him that too. I have asked a few people but they all say don't know either. I rather know if I did something dickish so I won't make the same mistake again. P.S. We're from the UK so it might be different from North America :s
<bot>: I told others about my ex who was seeing someone unofficially and he got annoyed saying I was rude and it goes without saying to not tell the whole world (which I didn't do).