thanks for all the good wishes everyone!
dogma was right; my ex is a woman. and, after a 6 year relationship, started screwing around within 2 weeks of our breakup. not particularly great for my self esteem.
she had a gastric bypass a few years ago and lost a few hundred pounds, but now has a raging case of bulimia. i changed my eating habits to be supportive of her (which is how i lost the 100bs). now, after she has been successful and moved on without a thought, i guess i feel desperate to get my own life back under control. getting rid of my excess weigh seems like a good start.
but i know i can't do it alone--
so thank you guys for the welcome.