I'm very sorry you're overwhelmed with depression at this moment. Are you on medication and in therapy? Would it be possible for you to put your thoughts on hold so you can work? When I've felt very overwhelmed, I found it helpful to imagine putting my thoughts in a locked box. The locked box means you won't think about the feelings until later. This is good especially when the problem not solvable. You could also imagine in your mind a beautiful relaxing place and do some deep breathing.

It may help you to know....... I know very well what's its like to go through an extreme relationship disappointment. You're grieving right now. Eventually I realized I wasn't going to let anyone destroy my life and this helped me but its a process of healing. I hope it gets better for you.