Why do N's flaunt their new relationships?

Hi there. I was only dating my N for a month, but lots of red flags I should have taken action on, but it was so subtle at first. I've done lots of reading and had responses to my first post that this guy is definitely a Narc! Luckily it only lasted a month because he couldn't bring himself to show me any empathy or support when I suddenly lost my dad despite me 'meaning a lot' to him and being 'special', so I questioned his behaviour and he was off faster than you can say 'go'.

Anyway, I saw he was back trawling the dating site two days after I told him he was selfish and only cared about himself (he tried hoovering as a last attempt). I saw he has a new girlfriend two weeks after this and it is plastered all over facebook....poor girl. No doubt he is idolising her to the point it makes me feel sick.

I had a nosey on his friends facebook tonight, don't know why, just a feeling (I won't do this again), but it just looks like they are all having such a cosy time, with his friend tagging the N's girlfriend in statuses to say how much fun they are having as a group. I did meet his friends once, only two weeks before it ended. It just seems like he is showing her off and she has fitted right in....just leaving me in the cold like I never existed. I know this is silly talk as I know it is all fake, but seeing it plastered on there is just like punching me in the stomach. Please give me some strengthening words! I can't wait for it to fall apart for them, but this is just my bitterness.