My ex nicknamed me Fat and Forty

Its hard to grasp how someone you spend years with can change the minute things don't go their way. I dated a guy for several years and a year ago I was offered a job out of state. After much consideration, we BOTH agreed this job, knowing it would be temporary would afford us the finer things in life and also pay for my sons college educations. BUT, as soon as I left, he turned nasty and renamed me Fat and Forty. He dumped me on my 40th BDAY. Things got so bad I had to change my number, email, you name it. Needless to say, he went back to his ex and has gained about 50 pounds, and I have changed my life, in all positive ways. I know I shouldn't find motivation for his letting himself go, but I can't help it, not after all the pain he put me through. Call me crazy, but it pushes me everyday on that treadmill.