what do you do when someone makes a fake child abuse claim against you?

The guy I am pregnant. It is upset over child support and has threatened and said that he will call social services and tell them I locked my son in a dark closet and yelled at him... I believe he's saying it all through text to try to have proof but it's not true and I even mentioned it being a lie in our text message!! What can I do to keep him from making up these lies and putting me into so much stuff with law enforcement... I want to get a restraining order but then he can still make his false allegations and I'd STILL have to deal with social services..
I already have an 11 month old (who he's lying about) and I am 6 months pregnant by him..