Totally agree with PPs, block block block.
You say that you "heard" about his new rship.. Did you actually hear about it through the grapevine, or did you see it yourself on Facebook? 
If someone in your own circle actually said "hey, I see Dave has got another girlfriend", you need to be forthright and tell these shit stirrers friends that you have no interest in hearing about what 'Dave' is doing now (even if you have).
He was no good for you, you said so yourself. When you ended the relationship, you did so because you knew were worth better.
And you still are! He hasn't changed, and neither have you- you're still worth more than his new girlfriend has set herself up to have with him, OP.
Cold turkey all the way. Delete his number, and clear your inbox of any old texts he sent.
You don't want to be sat quietly half-pissed one night and rediscover one of them.
Delete and block him on FB, and block her too for good measure.
And don't feel like you need to rush into finding someone else now, because relationship=happy, and single=lonely!
If anyone looked at my FB page now, they'd see me and happy smiling DH, a cover photo of happy, smiling DCs, and a pretty happy history.
But at home, things are pretty shit at the moment for a few reasons. People rarely present the full image of themselves to everybody, only cherry pick the best parts, because it's social media, not a Diary.
And she probably doesn't know a thing about your XP yet, she's to be pitied not envied.
I don't know about CBT purely to get over a relationship, I do think though that perhaps CBT might help with other issues that influence decision making, and if it is a pattern of behaviour (ie, naturally gravitating towards unsuitable men for example). Idk if this applies to you though, Flamingo.