Welcome Designer. I'm glad you found us and so very sorry for what brings you here. This kind of thing hurts beyond hurts.
Sadly many alcoholics can't face whatever it is that alcohol helped them hide from. Starting a new relationship can be a means to avoid the pain that they must go through to get to recovery.
Also the grieving that is required after such a big loss takes time. As much as you may intellectually accept the end of the relationship, your feeling will have to run their course. It does so so suck.
Please let us know how you get on and take the best care of yourself that you can.