I'm so sorry for your tragic loss of your son. There will always be times, but espescially the anniversary of the accident and particluarly holidays and his birthday that will be very emotional for you.
Maybe you could sit down with your family and tell them how hard it is for you and they could talk about how it is for them. All of you come up with some ideas for comforting each other and getting through those times when they occur. Talk about Chris during those times and talk about how you each miss him. Remember him and allow your grief and share and comfort each other.
You miss him; you'll remember him always. These times of grief and depression will be there but they will get better--easier, less painful, and less frequent.
My heart goes out to you,