It is very possible that after she had children she was not able to continue on a wife and the role of mom probably took a lot out of her. I never had children (by choice) but I would imagine it can put a damper on feeling romantic. She probably fell "out of love" with herself and it bled into your relationship. When the kids get a little older, it is then man and women can resume their romantic relationship. During that time, a couple can either ride the wave and when time allows, come back together. Sometimes this wave takes them to different parts of the shoreline. I apologize for using this analogy, its the only one that popped into my mind right now.
Some relationships are not meant to last a lifetime, even the ones that create life together. Choosing to have a family is a committment to create a life, then take responsibility for that life until they are creating lives of their own. During that time, a lot of sacrificing has to take place. Maybe you wife just got burnt out? Maybe she doesn't like herself anymore, heck, maybe she never did, and looked for happiness through your marriage and probably thought having kids would make her life complete. She may have used you to complete her, and that is always going to bring dissatisfaction because when we look outside of ourselves to find happiness, love and acceptance, and not really have it inside to begin with, we will never be content. If she is lacking in hygiene and gained some weight, what a lot of people may suggest is treat her to a day at a spa where she can get a wax, a massage and a healthy lunch. Then buy her membership to a really nice gym and get her a sweat suit. The rest is up to her. You can't do anything outside of helping "her" help "herself".
I am of course, only giving you my opinion and not knowing either one of you, it is not fair to give advice, but from what you say, if this has been going on for a while and the two of you have covered over the bridge that connects you together, it will take more work to clean up the mess. Thats why its really bad when people can't work out their amigo image together. That is what psychologist call when a person keeps picking out men or women that treat us like our father/mother did. How was her relationship with her dad?
My dad used to pick on me a lot. That was how he expressed himself to me. I don't remember too much recognition, praise or attention coming my way from him. So what I now am attracted to, even though it is disasterous to my love life. I am 48 and still having "love " problems. Our problems are our greatest gifts because then we can see how we want to change the course. If we don't notice the problems, ignore them, run, look for band aids, we are losing out on a real chance at happiness. Its scarey to possibly look foolish, childish or stupid, but if we think that just because we don't tell anyone, (hide behind falsh promises, porn, denial, affairs, food, lack of personal caring) that we can "fool" everyone, ourselves included.
I would suggest offer her a hand, if she doesn't take it, stop waiting for her to!!!!! You are not being a bad guy by wanting more out of life and I am sure you hate that she is so unhealthy but there is NOTHING in your power to make her move on making changes. She is content where she is, even if she is miserable. This is her choice.
You have a choice too. Stop thinking about her armpits and fat, and start looking in the mirror. See whats there. The answers come a lot faster when we ask the right questions.Do you feel you deserve better ?Do you believe someone else will be able to make you happier? Now look at the mirror and ask yourself are you so sure you are not looking for yet another diversion (problems in your marriage) to avoid confronting your own fears and weaknesses/and or desires? Once you remove her from the equasion of cause of your happiness, you will find ways to love yourself, and it won't be through porn. That is just a rebellious act and you are mad. :)
I hope I didn't confuse you but what I am trying to get at is try to take the focus off what "she" isn't/is doing and take a close look at how you want to run your life.