How do i know what network administrator can see on my computer?

[thenewsusieq]

Thanks for that - not great news but at least I know i was right to be worried - and yes, it is on a domain.

[michaewlewis]

Another simple solution is to use a different operating system, like ubuntu, which would be harder to break into, especially if the ex is a windows guy.
Also, turn off your computer when you're not using it.

[thenewsusieq]

Is there a way of disabling his administrator access from MY computer?

[Aegis]

Do you NEED internet access for your work?  Do you use any files located on his computer?  (I'm guessing "no.")