The biggest thing you need to do at this point is document. First, I would contact the state police if the local police cannot help you. Second, are you and the ex in the same state? If you are then stick with plan A (state police). If not move to plan B, the FBI. Since the hacking will have occurred over state lines, the FBI might want to get involved especially since he is interfering with your business. If you are all local, I would take him to small claims court. Present the evidence and get a judgement. The first time might be painful but once the process is solidified, you can take him back every time it happens. You will only get about $2500 per event but you can go back time after time and it will add up after awhile.
Next, I would start reading up on how he is doing this because until you know what he is doing you will not be able to stop it.
Together is where I want to be...
The FIRST thing to NEED to do, is shut OFF remote access on ALL computers, change the WiFi encryption, and use altered passwords for every Email and web account you have.
Try using a VPN server, and talk to your ISP and infor them of the intrusions, and if possible from your side, log the external accesses into your IP from a remote server/VPN or any other point of intrusion.
There's always a method to track and identify any intrusion, look into your log files, something has to be there.
if he has the capability to do this, then he can also begin DDOS attacks with some feeling of impunity.
Using ANY communication device on ANY public network to spread fear or intimidation or threats is a felony, and a federal one on top of that, the FBI gets called in and will find him!
I wonder if he has access to, or owns a current communications service monitor, like the Aeroflex 3920 series, which can test encryption, digital radio and certain cellular data systems.
I personally have three service monitors, and the 3920 IS a very capable service tool, but might be too costly for a hacker to purchase, as mine was $39,000.00.
These are points of interest you can investigate, and if he's stalking you, he may be into more serious criminal activities than you may be aware of, and quite possibly attempting to associate you and your wife with his criminal dealings to hide behind.
The longer you allow his leash to become, the more difficult it will be to nail him down, so do all you can NOW, to minimize the damage he IS doing to you, then make him pay!
I wish you and your wife great luck in these matters, as NOBODY should be forced to deal with psychopaths like him!