-Well there's few types of psy-vampires and not all of them need an emotional connection (link) to you. There's the life force feeders (prana energy), the negative energy feeders (feed of stress, hatred, and everything else negative), the emotional feeders (feed of pretty much every emotion also the type that needs an emotional connection to their prey), the sexual feeders (sexual energy) and finally the elementals (they feed from the element's energy).
-You can steal your energy back only if you know how to manipulate it and work with it. Not everyone know how to work with energy....
- Define "leave them"