How can any man do this?

I'm 7 months pregnant, my partner and I split up 3-4 months ago and he is now in a relationship with someone else?

He hasn't bothered with me or even asked how scans etc have went (has only attended my 12 week scan) he messaged but to ask the sex of the baby and has him flaunted all over social media, but yet has not once text to ask how the pregnancy is even going? His new girlfriend is also aware im 7 months pregnant? I'm baffled on the situation. I'm not hurt at the fact he's moved on, I'm upset he hasn't bothered with his son, but will flaunt him on social media as if he's involved etc.. & hasn't contributed to a single thing?

I have tried to mentally and physically heal from this entire situation & he couldn't be assed.