My ex objectified my friend less than a week after dumping me

I know they say men post break up have fun now and regret the breakup later, but honestly, is bumping into my friend in a bar days after breaking up and commenting on how my friends cleavage was catching his attention, knowing full well she was meeting up with me - an ex’s idea of fun?

We (28M and F) were in a solid 3 year relationship where we spoke about the future and shared our deepest secrets and insecurities, 2 of years being distance. Ended amicably ish about a week ago over family/relationship conflict amongst a few other things but the next day he was very bitter and hateful towards me and reported to have no hurt or love left for me. There is a lot more context behind the breakup, and the more I think about it the more I realise there were suspicious things that I overlooked at the time, but in hindsight I should've paid more attention to.

The way he spoke to my friend like that (totally sober btw), not long after he told her about our split, just makes me feel like our relationship meant nothing to him. Was he saying it knowing she would tell me and I’d get insecure about it (I’m not exactly blessed with a great chest)?? I can’t understand the male logic behind it. I get he’s newly single, can do what he wants but surely that is a clear disregard for what he has walked away from? 

Please share any insights of the male dumpers post break up brain when it comes to interacting with girls. Did he move on from me fast? Did the 3 years mean nothing? Is he even capable of regretting it later/reaching out to me? Because as messed up as this is, the feelings for him are very much there. Please advise a girl whose self esteem is completely and utterly on the floor! Thanks in advance