Lost my favourite
Hi and welcome to beyond blue.
firstly let me echo the comments made by Sophie_M - I can tell from your post the relationship between your father and yourself was very close and special, something to be cherished.
You posed the question Why now? Some questions are difficult to answer. The grieving process may occur after the event, or the much later. There is not set timetable either. For today, it could have been a sound, a smell, or something that triggered my memory. Whatever it was, for you is also normal. Sophie_M provided information on some groups to get in touch with - talking to your friends perhaps asking them for support and perhaps a local support group. There are ways to get through this period of feeling low. Other people here will also lend their support to you.
Listening to you tell your story,
Trying to beat it,
Welcome to the forum and thanks for making your first post.
Sophie and smallwolf have made helpful suggestions.
My dad died over 13 years ago and I miss him each day. What I found helped me was to write a letter to him, I did it on the computer and tell him how I was feeling and things that were happening in my life. It helped me as I felt he was part of my life , I wrote for a couple of years and now I may write once a year. It really helped me in those first few years.
It is hard but I found including him in my life by writing to him helped me.