Absolutely, you CANNOT ransome visitation for support. Your husband has an absolute right irregardless of payment of support to regular visitation thank God.
Please try to remember that in any divorce case, the court will always rule as to what is IN THE BEST INTEREST OF THE CHILDREN. Now think. It it in the best interest of the children for you to deny them the right to see their father because of money payments? Are the children mere merchandise to be bargained?
I belive you are bigger than that and you (your children) are most certainly entitled support. You might have to enter the "system" (government support) in which case intake will pursue child support from this dead beat Dad like a tiger on a lamb. Good luck and thanks for posting.