Sorry he reacted so heavy handedly . He sounds very mixed up if he thought he could just walk back in and yet he can't commit to seeing the kids. Well done you for being so firm.
Your solicitor should at least be able to put what you have agreed on a legal footing or work out an interim maintenance payment, should CSA prove slow - he'd need some paperwork showing income and outgoings but can demand that directly from AH.
Take care, you have come so far.