the rule on support is that it must be a balance between the needs of the person claiming support and the capacity-to-pay by the person giving support. as to where that balance lies, only evidence and the court can tell.
the thing is, you are still married to your wife. you also have a child with her. under the provisions of the family code on support, you are obligated to support her and the child.
it seems to be a problem of how much can you be compelled to give as support. you can either 1) negotiate with your wife as to what the reasonable amount is, or 2) wait for her to file a case for support against you. and the end the day, you cannot be compelled to give all of your money to her, just a reasonable amount.
be reminded that you can always choose to have the child live with you. it might be cheaper for you and you can better monitor the costs. the wife might be padding the costs or worse, using the money for things other than funding the child's costs of living.
as for her threats, remind her that if she disagrees with what you can give, she can always file a case for support. her acts of threatening you at home and at work, you can file a criminal case against her.
see articles 194 to article 208 of the family code for reference.
at the end of the day, these things should be tackled with patience and peaceful attitude. threats and harassment will only make things worse than it is. try to talk her, and strive to settle things amicably.