Guardianship

Hi po meron din po ako katanungan.. My husband and I were separated a long time ago. I am now divorced and I live in canada. We have 3 children 15, 13 and 9 years old. When I left the Philippines 2006 I left my kids with my aunt. And it's just recently that my ex went and took them from my aunt. Now my problem is he has no permanent job, he is living with his parents, he has a drinking problem, he smoke. Can my kids choose not to go with him or do I need to file for custody and appoint my aunt as the legal guardian for my kids.. Do I need to file in person or can a lawyer do it from canada.. Please help I really need help bad.. Thank you