No wonder you are feeling depressed. He was your first child and his departure marks a full cycle of motherhood. This transition alone would cause significant upheaval in your household, but you have not only lost your eldest son, but your husband's presence in the home. At the same time he has lost his father's daily presence. He is a boy left alone with a grieving mother.
Anger often masks sadness.
Instead, talk first with your husband about your own feelings of abandonment. You are launching your first child without the loving presence of his father for easing the pain. You and your husband have shared raising him together, but you are apart for this major transition on the family's life cycle. Depression and a strange sense of emptiness are common for parents at this time. Share as much of this experience with your partner as possible.