If you do even one little thing to crack the door open.....first they start with a toe, then their whole foot....then they are walking right back in like they own you and the whole world.
They need to know that NO CONTACT is firmly and undeniably in place.
NO MATTER WHAT
The only way I could do this (at first) was to pretend that my daughter was dead.
I know....it's morbid sounding. But the whole addiction/manipulation thing is crazy and worse in the long run...because it keeps doing damage over and over....to them and to you.