I am very glad you plan to see an attny. You live in BC, correct? If that is correct your H may be way off base with his plan of not having to pay child support if the custody is split 50/50.
When determining support for "split custody" (this was defined as more than 40% of the time so the 50/50 split would fall under these parameters) the amount of child support payable is the difference between what each parent would have to pay the other for the support of the child(ren) while in their care.
I will use the numbers in the table provided by the court:
If your H (PERSON A) would owe you 1000.00 per child for support while the child(ren) are in your care and you (Person B) would owe your H 250.00 per child(ren) while the children are in his care the difference would be 750.00 and HE would be responsible for that sum to you and you would pay nothing to him. It is essentially the amount Person A pays - minus Person B's obligation = amount Person A pays.
In 2005 the Supreme Court of Canada ruled on a case called Contino vs. Leonelli-Contino and that case changed everything in the courts. The ruling basically said the Guidelines table amounts must be respected as a whole and if the payer (your H) is to ask for a reduction from the table amounts the burden of proof falls on him if he meets the 40% shared custody time. There was also a case called Van Gool vs. Van Gool in 1998 where undue hardship was defined and it is not easy to claim (undue hardship or the proof of is required to ask for the reduction).
Also, your son's special needs may be a consideration when determining the amount and length of support as he may not be able to support himself once he becomes an adult.
And, child support is not a supplement for spousal support and that is a whole different table and one cannot determine the other.
There was page after page of particulars for child support so don't do anything until you talk to an attny. 50/50 (or more than 40%) does not necessarily give your H a free pass not to pay support.
The two cases I cited above were on every piece of information I read so clearly the court in Canada has decided no BS when it comes to people trying to find loopholes when it comes to children and their financial support!
