The 50-year-old actress eldest son Dashiell, 18, is preparing himself to leave home and head off to college later this year, and Cate has said she's finding it "difficult" to come to terms with the idea of her son leaving the nest.
Asked about her son's college plans, the 'Where'd You Go, Bernadette' star said: "Do you want to see me cry? It is truly a huge event. Sometimes I get asked what is the most difficult thing for a parent ... I think it's letting them go, being able to do it. My mother often told me - and I regularly rolled my eyes - 'You will always be my child, I'm sorry, I don't want to treat you like this but ...'. Now I understand perfectly what she meant. It is difficult to break away, very difficult, but I am so proud of my son. Of all of my kids, to be honest."
Cate - who has Dashiell, as well as Roman, 15, Ignatius, 11, and adopted daughter Edith with her husband Andrew Upton - doesn't know "what [she] will do" without Dashiell around the house, but is confident her son will "always need his mother".
She added: "Now that my son is 18 and I wonder what I will do. 'Dashiell no longer needs me,' I say to myself. And then I think, 'No, he will always need his mother.' It is up to us to redefine the relationship we have with our children and allow them to grow up, to become adults. If not, we'll get another dog!"
The 'Carol' actress says having four children and two overworked parents can create "chaos" in their home, but admits she feels a "perverse attraction" to the hectic life they lead as a family.
Speaking to Italian publication IO Donna, she said: "I feel a perverse attraction to chaos. Both my husband and I are freelancers, it is difficult to for us to plan and organise, we're fine for around six months and then suddenly we'll be crying: the pilot flame in the kitchen won't ignite, no one knows where the matches are ... They are not real problems, but they are the small things you have to rely on to keep going."