Hello, I'd like to help you with your question.
It sounds like your husband is still grieving over the loss of his father. The grief process is different for everyone. Some people work through their grief quickly and move on, others grieve for a while, sometimes for a few years.
As you may know, there are steps to grief. Some people follow all the steps, some skip a few or feel them in a different order. But it may help you to know what the stages are. Sometimes, people who are grieving get stuck in a stage and cannot move on without help. That may be the case with your husband. So understanding what the stages are can help:
Denial: “This is not happening"
Anger: “Why did this happen?"
Bargaining: "If I do this, then the person will come back"
Depression: “I can't cope. I feel too sad"
Acceptance: “It's ok that this happened."
The important things to look for with your husband is whether or not he seems to be progressing or working through his grief. If he seems unable to face it (such as not being able to talk about it or avoiding the topic) and seems preoccupied or lost most of the time, he may be stuck in his grief.
You mentioned being supportive of him and letting him talk. That is good. He needs to be able to process this so he can work it through. Your support makes a big difference.
Talk to him about whether or not he feels he needs to talk to someone like a counselor. Encourage him to at least try a few sessions to see if it helps. To find a therapist, have him ask his doctor for a referral. Or you can search on line for a grief counselor at http://therapists.psychologytoday.com/rms/.
When you seek a professional, look for one who has a Master's Degree or a Ph.D. Either one can help. A psychiatrist is great if you feel he needs medicatons, but otherwise a Master's or Ph.D level mental health therapist can help.
It may also help to get support through on line or in person support groups. Here are some links to help:
Here are more resources to help you both understand the grieving process and how to work through it:
Healing After Loss: Daily Meditations For Working Through Grief by Martha Whitmore Hickman
On Grief and Grieving: Finding the Meaning of Grief Through the Five Stages of Loss by Elisabeth Kubler-Ross and David Kessler
You can find these books on Amazon.com or your local library may have them for you.
I hope this has helped you both,