Prepare to discover he is not who you thought he was.
Do not believe a word he says from now on. Do not trust him.
He deceived you over how he was supposedly feeling for a long time, while he carried on playing happy families, hiding the truth, giving himself time to adjust and plan while all along intending to drop a Christmas hand grenade into your unsuspecting life, didn't he.
He is not your friend and does not have your best interest at heart.
Expect him to say he wants to have your child 50/50. They do this. Generally to get out of paying maintenance. In practice, you'll still have the bulk of the care work to do.
Do not let him say oh we can do this between ourselves, we don't need the expense of a solicitor. This is generally to get you into a corner, believing more lies about your rights.
As soon as they open again, consult a solicitor. Find out about your and your child's rights and his responsibilities.
If his parents / family are around, be proactive and tell them yourself what he's done. He will be going full steam ahead to try to minimise and twist the narrative. And expect them to be firmly on his side. He's faaaaaaaaamily.
Tell your friends (you'll learn who/if they really are, shortly). You'll need your team.
And he can swear til Armageddon that there's no-one else, but there will be something going on beneath this.
The shock and denial will subside. Find your rage and resolve as soon as you can.