Hello love, it's only when we get out to the other side that we look back at ask 'why on earth did we put up with that?', it doesn't change the fact that we did because we believed in loyalty, commitment and supporting others. These are not criminal offences, in fact these are qualities in people who have decent values. So stop blaming yourself, and start congratulating yourself for getting out.
In reality, as far as I'm aware, the child has a right to spend time with both parents - so given your concerns you will want to be thinking about 'supervised' contact in a contact centre first of all. It's not just what he says that is monitored, but his behaviour too. Get yourself down to the CAB for more information.
You say you don't know how to prove it, but if there were carer's witnessing it, you can easily prove this. If you've had SS involvement - there's your evidence. IF, and that's only IF, he takes you to court for contact, then you'll get a CAFCASS report ordered (most likely) to whom you can discuss your concerns.
Can I ask you, if you haven't already, to contact Women's Aid? Also Rightsofwomen.org.uk. These organisations are experts at helping women coming out of traumatic relationships. It will only cost you a phone call.
If you are asset free then there won't be any Financial action to take. You can apply to CSM, I think it's called, to chase him for some income support, but that depends on whether he has a job.
You don't need to poke the Hornet's nest yet, but I'd strongly recommend you talk to the organisations I've mentioned here so that if you decide to divorce, you are fully aware of what that involves, how to cope, and make sure you can access support. Good luck.