I wanted to respond to your post because I used to dysfunction very much like your ex-girlfriend except that I had the very good excuse (not )of "Hey, I put on the 30 lbs. having your kids. Cut me some slack.". Anyway, like most situations it was one where you were both in the wrong. The error of your GF's ways is obvious to both of us. Maybe if I can show you the error of your way in that situation it will help you with whatever situation you are in now.
Consider first what happened to your GF after you broke up. I suppose that there is a small chance that she is still living alone with her cookies but probably either A) She found a guy who likes a lot of cookies a lot too who did want to f*ck her at her higher weight or B) She lost the weight after the two of you broke up. If the answer is A) then it's a pretty simple case of incompatibility and lack of shared values and it's a good thing the two of you didn't get married. If the answer is B) then the question you might want to ask yourself in a similar situation is "Why would a woman find eating cookies more emotionally soothing than being in a relationship with me?". The exact same behavior that would cause one woman to start munching on the cookies will cause another woman to shut down sexually, so this could be relevant to your current situation if you are the HD spouse.
Also, consider the following. Let's say for the purposes of my illustration your GF was 5'5" 125 at the start of your relationship and 155 at the end. Okay, a while after you break up with her you're out at the bar or on the internet looking for someone new. Two women are looking at you like they might be interested. One is 30 lbs slimmer than the other. Because you are "chemically" attracted to slimmer women, you would choose the slimmer one, right? However, part of what you said is that you highly value healthy living and physical fitness. What if you discovered that the slimmer woman maintained her weight by smoking and drinking to excess? Would she still be a good candidate for a long term relationship? Would she lose some of her "chemical" attraction? What if you met a woman who was 5'5" and weighed 150 lbs. but worked out a lot, enjoyed physical activities, had a muscular, well-toned body and was a gourmet health food chef? Would the simple fact of her "size" still be a huge turn-off? I think that your GFs lack of respect for your values had as much to do with your LD for her as her weight gain.
I think the same thing is true when it comes to the double-standard you mentioned for men. For instance, women frequently want to f*ck starving artist types. It's the lack of initiative or confidence or ambition that turns them off to men who are "bums", not necessarily the lack of money.
"Tell me, what is it you plan to do with your one wild and precious life?" - Mary Oliver