Cos-3 Google have confirmed by gmail account has been synced also.
How did you confirm this? What devices are your gmail accounts synced to? Did you follow these steps? https://support.google.com/accounts/answer/3067630?hl=en
Cos-3 I lost access to my computer that i had before i met him, due to global policy.
This doesn't make sense. Is the computer no longer in your possession? Does your ex have your computer?
Cos-3 I found he was using Direct wifi, ethernet and NBN. I found he was using a phone to set timers.
I doubt he was using any of those to attack you. If you're paranoid about it still then call your current local internet provider and ask them for support regarding resetting your wifi/internet.
Cos-3 He was also on the deep dark web.
And how did you find this out? Did he tell you? Also, just because he may have been browsing on the dark web don't mean he was doing anything to harm you, he could have been using Tor for privacy purposes, research, etc. Many journalists use Tor regularly.