Hi, yes, your post makes complete sense to me.
I ended my marriage after over 10 years together (4 married) last year.
I'd had a depressive episode when I was younger, before meeting EXH, but had many more during our time together.
It's very difficult to say what makes people depressed- its a huge catalogue of things and I don't think it can be pinpointed or 'blamed' on one particular thing or person. In my case, I would say it's genetic, but also that my relationship with EXH didn't help (feeling that he didn't find me attractive/I didn't find him attractive, not feeling appreciated, that there was no romance etc).
No we're separated, and I certainly feel better generally - I don't miss him, even though looking back, he wasn't a bad person - HOWEVER, I would focus on some sort of therapy if you can to sort out why you feel the way you do. I'd say that a lot of my depression stems from low self confidence and you need to work on that before anything else.
Although I feel better that I'm out of the relationship with EXH, the sad thoughts I had whilst with him have now been replaced by new feelings of anxiety regarding finding someone new. I've been online dating and the experience is pretty brutal - for the most part, it's made me more down...
Sorry for the long post. If you need to chat, just PM me.
Hugs