Click on this link www.womensaid.org.uk/domestic-abuse-directory/ scrolll down to find your nearest Women's Aid service and make contact asap. Alternatively, google your local council/authority to see if they have a domestic abuse unit.
Assuming that you didn't marry this abusive twat, is he named on your dd's birth certificate?
I've told him so many times that I will only respond to things about the dc, so he either finds things to ask about them all day to try and engage me in back and forth messages or he says things that he knows provoke me and I will feel the need to defend myself or correct what he's saying
This is the way he grinds you down and the more you respond, the more control he believes he has over you and he won't stop until he gets what he wants - and when/if he gets what he wants he'll come up with a whole set of new demands which are guaranteed to grind you down etc etc rinse & repeat.
As you sound on your knees, I doubt that you'll be able to grey rock him alone as you seem fearful of what he might do if you endeavour to keep him at arm's length.
He's a bully and, ime, the vast majority of bullies are cowards. Keep all of his written communications and don't hesitate to call the police if he kicks off in front of the dc.
Do not allow him to enter your home. All pick ups/drop offs must be on the doorstep or, preferably, done through a third party.
If his behaviour is upsetting your dc, withhold contact and tell him he'll have to regularise contact through the courts.
However, as that may result in him snatching your dd or failing to bring her back after contact, I strongly urge you to talk to a domestic abuse advisor with a view to obtaining a residence order which will enable the police to return your dd to your care if he fails to return her and a non-molestation order which will prohibit him from making contact with you.
Also talk to the advisor about getting the police to have a word with him about his harassment of you as they have the power to put him on notice that, if he continues this behaviour, he may find himself up on a charge.
He should NOT be allowed to bully, intimidate, or otherwise harass you and I hope that, with the help of those who are only too familiar with this behaviour, you'll find the strength to put him in his place.