Having just been through a breakup, I'm a man, cheated on by my partner, I really feel your pain, and yes, of course you connect to the child as well, I did.
At 12 weeks into this myself, here's a bit of my homespun wisdom.
1/. You cannot control other people, he decided to do this, if it came more or less out of the blue, or even if it built - the relationship wasn't working, and would have faltered eventually.
2/. A clean NC break is very painful, feels awkward etc. but is acknowledged to be the most effective method of disconnecting.
3/. However much of a bond you formed with the child, you have to accept they come together, the child is not yours, not old enough to decide to stay in touch, and outside of your control - you must let both go, that is double the pain.
It WILL get better, there ARE great times and happiness ahead, but the coming 6 months or so will be a bit shit, concentrate on yourself, moving back to your place etc, keep NC, no socials etc. move on.
Take care!