Sorry to hear this, it's certainly not what you guys need right now (or at any time, really). I can empathise with the whole anxious/aggressive pet = unwelcome, but necessary change deal: Jezzie will now rarely be walked off the lead and has to undergo quite intensive re-training (she happy because it's food based though, and she loves food more than her freedom!). According to the 'dog whisperer' it quitely likely has a lot to do with the attack you witnessed when she was a pup.

BTW, I echo Kate's offer of any kind of help can lend - just say the word!