You're not wrong. She sounds like a controlling b*tch, the way you describe it.
Are you sure there's not something else you're not telling us??
Puppy
Ditto. And from what I gather, you're both overweight"? If so, she's either threatened or intimidated by you losing weight while she stays fat. Kinda like when two are alcoholics and one stops. It changes the dynamic. And it's no longer "We're the same, so nothing's wrong." It now becomes "Hey, I'm the drinker."
And, yeah, she sounds like a controller.
Gardener
"My soul, be satisfied with flowers, With fruit, with weeds even; but gather them In the one garden you may call your own." Cyrano deBergerac