Gmail stuck on my ex-boyfriends android?

[Joe Kunnummyalil]

Check if he is forwarding your emails to his email. Goto gmail->settings->forwarding. remove any email forwards.
Create a checkpoint in Facebook.(account settings->security->login notifications) it tells what device is entering your Facebook each time they login.
Create a two step verification process for google accounts. goto google accounts->two step verification
Change your secondary and recovery email from your gmail and google account .
goto https://market.android.com/account and update your device and cancel any other systems.