For all I, you, etc. care - Idioms by The Free Dictionary
for all I, you, etc. care
for all (one) cares
One does not care (if something were to happen). The phrase always precedes or follows some hypothetical situation. You can starve to death for all I care. I am not giving you any more of my leftovers.
for all I, you, etc. ˈcare (spoken) used to say that a person is not worried about or interested in what happens to somebody/something: I could be dead for all he cares!