What do I need to do if husband cancelled all medical coverage so that he will receive more money in his paycheck for himself?

This is a concern that crops up frequently, so I am glad you asked. Because you and your husband already have a separation order from a court that requires your husband to maintain medical and dental coverage for you during the separation, his cancellation of your coverage constitutes a violation of the court order, which can subject him to punishment for contempt of court. To have your husband sanctioned for contempt of court, you file what is known as a motion for order to show cause. That motion is then served on your husband who is told he must come to court and to "show cause" why the court should not punish him for violating the order that we maintain insurance coverage for you. The court also ordered him to reinstate your coverage or face fines, a jail term, and other punishments the court can mete out.

You can seek a court order for Husband to reinstate coverage (if available to him through his employment at no or reasonable costs) or you can consider a contempt action if cancellation is a violation of your judgment (which in most circumstances does not get you health insurance coverage but other remedies fine or jail time).

Tell him you will file contempt charges if he does not get it reinstated. And then do it if he does not cooperate.

File a Motion to Enforce Final Judgment with the court.

If your "separation agreement" was memorialized via a "Judgment of Separate Maintenance" that was signed by a Judge, then you should ASAP file a Motion with your assigned Judge to seek enforcement. However, if your "separation agreement" was simply a written agreement between you and your husband, and was never the subject of formal legal proceedings, then you must either file a Complaint for Separate Maintenance or a Complaint for Divorce (depending on your ultimate goals/intentions), and request the Judge to order your husband to "re-up" the previously-existing medical coverage for you and the kids.