Although my relationship was much shorter than yours, I too have been through a recent separation, and I know how your world can be turned upside down.
My ex-partner had depression (as a result of a underlying medical condition) and for the last six months of our relationship, our connection was absent and our relationship was ultimately neglected.
My ex just became so preoccupied in his world of online gaming and wouldn't spend any time with me. The mortgage repayments fell to me on my sole income and all the household chores as well.
It is so difficult when an event happens that shakes and disrupts all the dreams you had for yourself and this person. I had wanted to marry this guy, have his kids and go on lots of adventures with him. But the man I had fallen in love with disappeared, and in his place was a husk of his former self.
I still loved him, no matter the form he took. But he wouldn't get help, no matter the nights I begged and cried to him with my head in his lap. And you can only lead a horse to water, you cannot make them drink. I had to come to the conclusion to look after myself, because that is what I ultimately had control over.
And as I learned, you need to re-orientate your thoughts to focus on yourself and what you need in this present moment. Your partner may very well be depressed and unsure of himself - and so if you feel you want to, maybe bring this up to him and offer your support.
But as my experience shows, you can only do so much. And you need to see yourself as the most important person in your life at the moment.
It can be hard, but be sure to still make time for the things you ordinarily love doing. If you have a dog, and simply enjoy going for a walk, do that as much as possible. Go to a movie by yourself or with a friend. Spend time with your children.
Do what makes you feel 'light' inside. There are obviously things that need to be on a transactional level - i.e. the house and things like that. But be sure to really take time out for yourself - make a conscious effort to give yourself the time to feel how you feel, and then time for happy, enjoyable things.
It is indeed a process - one that I am still dealing with - but good things can come from times like these.
I am sending you all my best vibes and hope to talk to you some more should you want to.