Your situation really sucks. The most important part is to tell yourself you can be happy again, even if it feels very far away right now. Being happy is the best thing there is, and worth a lot of effort and tough times to get to again.
Life gets overwhelming. You don’t need to see the whole staircase to take the first step. You’re doing your best. Be sure to talk about your feelings with your SO.
There is a mentalhealth community. As you’ve said, sometimes it is really good to write stuff down. Best of luck to you my friend.