Well a start would be to change your internet browser so he can't track your internet usage or use stat analysis software to determine what you are doing, TOR is a browser which can help you become an anonymous internet user but you will need to change you computer habits as well if you use it, It just a recommendation.
It can be downloaded here: https://www.torproject.org/download/download-easy.html.en
You say he is using spy software on your phone?, This can be deactivated or de-registered as most spy software requires the consent of the user which he could have given if he got hold of your phone. Other recommendation / new number and new phone.
Is he a computer hacker or does the wanna be twit claim to be one?, If so (AKA: He is one and you know it or he knows people) then you will need to phone a friend (land line please) and schedule a chance to use their computer to set up a new internet account. On a site who takes your security seriously, choose from here: http://freedomhacker.net/list-of-secure-email-providers-that-take-privacy-serious/#.U1VHDqITRBE
The most extreme level of moving to complete anonymity would be to buy a new laptop and start from there, Install TOR for net browsing and by using a new machine that way any spy wear on that machine you are using now will be hopeless. But make sure you don't use any software disc's (Burned ones) or external hard drives or USB's that you used on this machine on the new one because certain program are like STD's they are just transferable from one machine to another via swapping a USB from one machine to another. The good thing with a laptop is that you can also turn off the wireless card easily than on a desktop computer with a case, why is it good? Because if you read about TOR they say certain things like if you want to view a pic JPEG,etc, do so when the net is off or you could reveal your destination to this wannabe twit, it would already be difficult since the machine is new. further install software to protect your privacy such as TrackMeNot which prevents Search engines building a profile about you. PLEASE NOTE get someone to read this an possibly set up your machine for you before you use it, I don't know how good you are with PC's but an IT friend would help.
Website with potential software: http://www.pcworld.com/article/237027/best_free_software_for_protecting_your_pc_and_your_privacy.html
You internet is another issue, you haven't specified whether or not you you are sing a line or a USB 3/4G card. If you are using a line its time to switch internet providers, this will prevent him doing anything with your machine with regards to details he might have about you from the ISP.
Deal with this douche!, No seriously girl you must and I'm talking legally not web warefare. If your kids are at risk then its up to you to take the steps necessary to make sure they safe and that their privacy is respected as well as your own. Shame hope this comes right, such a pitty some guys become so insecure, douchie and creepy.. Don't worry we not all like that :) Your love of your life is out there (Many of them infact, you just gotta find one.)
Message me if you need more info.
To fight a hacker you need to remember that its all strategy like chess, If you can be aware of what you doing and not slip up then you should be fine. This is however easier said than done if you are not a PC or tech boff.
Go well. x