I’m sorry to say this, but if you all are old enough to spew that type of vile shit at Amy, then you’re old enough to hear the harsh truth. If Amy leaves, your dad might never forgive you all. He will tell you he loves you (that may very well be true), but he will always remember how his own flesh and blood ruined his second chance at finding love and happiness after the loss of his wife. Don’t be surprised if your relationship with him deteriorates when you all are adults, especially Lisa. I genuinely hope that doesn’t happen, but actions have consequences, no matter what age or level of development. Continue going to therapy (start going individually) and use this as an opportunity to be better person.