I am sorry you are feeling so sad Lulu. It takes time to work through feelings after a breakup and so many years in a relationship regardless of whether the person is an addict or not. Be kind and gentle with yourself and if the depression does not lift on its on maybe see your doctor. After my second divorce I went on meds for a bit and it really helped me get over the hump. I thought I would never heal - ex ran off with an employee 20 years younger than me to another state. My self esteem was trashed completely. This was 10 years ago. Took me at least a year to really heal. Now I can think of him with neutrality and good will believe it or not. If I had stayed with him my life would not be what it is today. Healing comes it just takes time.
Remember you are WORTHY of love and a healthy relationship. It will come someday just give it time. You were treated like crap because your ex has issues and is a cruel person not because of anything you did. It took me a long time to realize that some people are just rotten and mean period. You can't fix them with love, kindness or consideration. They don't care what damage they do. He owns this behavior NOT you. You are free now to get on with your life - give yourself the wonderful things you deserve. The old dead bones of that relationship will be buried in time and you will be at peace.