NJ's the is best advice.
Wipe the device: How do I wipe the BlackBerry using Jl Cmder? - BlackBerryFAQ
Then set a password as advised.
Do a complete backup of the device first using Desktop Manager, and then after the OS is restored to the device, use DM to Restore/Advanced only the address book, calendar, etc., as none of that is going to have any spyware in it.
If you want to do a first look at Options > Advanced > Applications, if there is any spyware loaded on the device you might noticed some odd application there. Ask here if you do, stating the name of the app in question.
Finally, the ex-husb may just know here email account password. Tell her to change that pw as well.