Hi Tennison and welcome to Beyondblue. I am so sorry for your loss. I have not lost my Mum so cannot comment on experiencing this type of grieving. All l can do is send you a big virtual hug and lots of love.
It sounds from your post that it is time now to reach out to family and friends regardless of your husband's depression. If he refuses help, that is his decision, but it doesn't have to be yours. My husband had depression for many years, and like you, I could not rely on him to support me when l was troubled. His depression was a 24/7 journey that l believe consumed all his energy, thinking and emotions. There wasn't anything left in his emotional tank for me. Therefore l turned to others to be my support. It was two close friends, but that is all I needed to get me out of the feeling of 'l am so alone'.
I also turned to online support groups on Facebook and sought out people who shared a common experience. I remained anonymous but gained so much from the experience. There are many grief sites available for you to tap into if what you need right now is support for this.
Can l also suggest that you see your GP and have a chat about your feeling and identify some coping mechanisms for you. Every little bit of advice could make a difference in how you manage your emotions and push through this period of your life.