Hi @Cadstar, Welcome to the forum, nice to have you here. You are in a safe place where experienced members listen and care.
I'm sorry to hear that you are going through this, I can understand and relate to what you are going through,13 years is a long time and a lot to deal with. I also went through a similar break-up of 20 years, it wasn't easy, I relied on my partner for everything. It felt like I almost had to learn how to talk and walk again. I soon realised I had to get on with my life, I was being so hard on myself, that I started to get sick. it took a long time but I got there! without turning to drugs or alcohol, instead, I started exercising, working on my health, slowing down, kept my mind and body occupied by doing fun things. I expressed my feelings and talked to family and friends. Also talking to a therapist helped me a lot.
Be kind to yourself, things will work out for the better, just give it some time. It would be nice to find out how you keeping up, I wish you nothing but good health, success and happiness, take care.