Anon - You've mentioned going through some major life transitions with your children and their father, as well as with your last long-term relationship. You said you have "empty time" on your hands that you are trying to "fill" with other things. You have concerns about your level of motivation for your job. It sounds like it might help to work with a trained professional counselor to sort out your feelings about all of these transitions and where you are now in your life, as well as where you want to go. It can be hard when we are in the middle of our own "stuff" to figure out the right balance, and - as much as we may like them - our friends are not always the best resources for dealing with the concerns that come with major life changes. You may also want to consider having a complete physical if you haven't had one in a while just to make sure that you're completely healthy.
You have a lot going for you, and are doing a lot of good things that will help with depression, but having some outside help and support to gain more focus on your "new" life and your future direction may help alleviate some of the anxieties that are leading to seeking ways to "fill time" and fill up your life. Hope that helps and good luck to you!