************************ Did I also mention that she is a co-worker (postal service) is thin and pretty, while I am overweight (working on for myself finally) and 42 years old. How do I compete with that ************************
It's great that you are working on it. I hope it's for the right reason (not him). I don't think it is a competition. At least not you Vs her.
Reach down deep and find the strength you need. Lose weight if that is your choice. Try to find a fun way of doing it. Don't live your life in fear of losing him. It's not something you can control. All you can do is create a warm environment for him to come home to. After that, it's his choice, his problem.