I know exactly what you mean as I went through the same, and it isn't just as easy as thinking about yourself, is it? I was in hospital, I was so bad at several points and it took me 1 year of severe depression and then another year and a half after that before I felt normal - so that's 2 and a half years before I could even contemplate doing enjoyable things for me.
That might not be great news, but honestly it's normal and I read somewhere that it takes the average person 5 years to get a completely new life after divorce, assuming that the couple don't get back together.
I don't know whether it will help right now, but if you have nothing to offer yourself, i.e, for your own benefit, you will have nothing to offer her and she will see that. It won't entice her to come back. My X despised me when I was depressed like you described.
Negativity does not attract a positive response. You have more chance of having an R if you GAL like crazy and genuinely start to enjoy your life, so that she will want to be a part of it.
My suggestion is to start by having little self-care goals, like that you will eat at least 1 cooked meal a day and try to take care of your appearance etc. They are the goals I started with, then you can add in other activities as your confidence increases.
I also think that you should surround yourself with friends. When I was as low as you, I found that being with friends helped to keep me calm, it's someone to talk to, distraction and helps the time go faster when you're feeling lonely.
