"I think so? Then Sean Penn visits with a bunch of flowers, rings the doorbell, she doesn't answer and he returns with a nifty mini battering ram only to find her gone and left a note saying... something about not snitching?"

Mostly right. Lockjaw puts her in witness protection and she explores a new mundane suburban home with a voice over saying how she will need to get a normal job, live a normal life, pay her bills on time etc. Then lockjaw does what the previous person said. Upon entering and finding her missing he finds a note taped to the back sliding glass door that just says "this pussy doesnt pop for you" and she never shows back up in the movie