I am so sorry. The loneliness is terribly difficult. The sadness was a grief like I had never felt before. It takes time to move through these feelings. But, my belief is they have to be felt and embraced so you can free your "channels." This allows the positive energy to come back.
I have always known how to be happy. We are living below the poverty level right now, but know how to be happy and appreciate the things we do have. We are thankful and greatful for the good things in our lives. This ability keeps me going and keeps me hopeful under hard circumstances. When you are feeling better, maybe you can focus on these things. Not sure if this will help you in any way. Just wanted to share it.
I'm sorry that you are hurting and grieving. I don't know if this is helpful. Just extending a hand and a warm hug.