DEAR HARRIETTE: My son is in college now, and it's really difficult for me to stop calling or texting him on a daily basis. A friend of mine reminded me that this is his time to begin to exert his independence. If I am too attached to him, he won't have the space to do that. She also pointed out that when we were in college, we didn't have cellphones, so it wasn't possible for our mothers to be so…