You can tighten up your stomach skin by buying some Retin-A (Retono -A) Tretinoin cream on Ebay or Amazon. It pops up several times a week for about $12-15 before Amazon pulls it. Ebay it's about $25 shipped.
You apply a pea sized amount everyday. Judging by your skin it will take a 6 months to a year to correct the majority of the skin fold but it's worth it. Not all of it will vanish as you have a good deal of shrunken fat (adipose cells) that are going to stay. You can get Laser treatments to tighten and zap the rest if you get sick of it. Total cost will be about $100 if you use 6 tubes in total. If you start to peal you drop it to every other day or every third day. If you can handle it you can apply it even 2-3 times a day. Your stomach will get a little red and you will eventually peal, then you cut back to where the skin is on overdrive but does not peal.
Millions of people use it to tighten skin and remove wrinkles. It's also used by pregnant women to tighten stomach skin after pregnancies. It works by increasing the blood supply and collagen and increasing cell turnover. It also helps in repairing newer stretch marks. Would cost you $100-150+ a tube by prescription. RetinoL is the over the counter much weaker (chemically altered) version that is not nearly as effective and does not penetrate deep layers of skin as well.
You wife would love it if she reads up on Retin-A. It takes 10-15 years off a girls face with time. It takes out freckles, age spots, liver spots, tightens skin, fine wrinkles and sun damage. I'm 49 and look about 30-35.
Search for these on ebay and Amazon:
Retino
Tretinoin cream
0.05% USP, 20g or 30g BY Johnson & Johnson
This is overpriced but the shipping drops to 2.99 on additional tubes.
This is the only .05% 20 gram on ebay today.
ebay.com/itm/Retino-A-0-05-cream-20g-NIB-/120980225094?pt=AU_Face_Care&hash=item1c2afbbc46
Here's a 30g .05 tube for $20 shipped but the seller has zero rating!
ebay.com/itm/Acne-Treatment-RETINOL-A-Intensive-Anti-Wrinkle-Aging-Cream-Retin-ol-30g-12-13-/110950778395?pt=US_Skin_Care&hash=item19d52e861b
Here's a 20g .025% <--- good for faces if you've never used it before. (half strength of the .05%) Seller has a good rating.
ebay.com/itm/20-grams-Retino-A-Cream-0-025-for-Acne-EXP2014-10gx-2-tubes-/150897275889?pt=UK_Health_Beauty_Skincare_PP&hash=item23222db3f1
Look at the $300 prices at costco
costco.com/Pharmacy/DrugInfo.aspx?p=1&SearchTerm=retin-a&Drug=RETIN-A