Hi LB, is he back in your vicinity right now? If he's continuing to harass you, take action as per Lexie's post to stop him. It won't be easy to build your new life if he's actively stalking you and the children. If you can take care of that part, maybe try to do some fun things with the kids, and for yourself if you can get a sitter. Assuming you're in the States, it might be hard before spring, but even going for a walk around the neighbourhood, or to a movie would lighten the mood. Fun stuff with children doesn't have to cost money as they love board games, or making cookies, you name it. Write down a few ideas.
Good luck with your losing weight, I hope you have lots of success. If find that cheers me up on it's own.