Had Full Tummy Tuck in June 2005 WLS 2 b set soon..

I had lost alot of weight through diet pills and had a tummy tuck in June 2005 before my wedding in Oct 2005 and I was well pleased ... But in May 2008 I was diganosed as being a Type 2 dibetic and have blew up like a balloon! I was 157 lbs at tummy tuck and now I weigh around 215... I am now going to see the sergon on April 8th for WLS (Gastric Bypass) and I am scared when I loose all the weight (90 lbs) I need to loose that my body wont be able to keep up with the pounds falling off and the money I paid for the tummy tuck ($4200) will be a waste .... has anyone experienced this problem? And since I had the muscles done as well will they keep my belly firm so when the weight falls of after the WLS the belly will not sag again? I am really happy still with my tummy tuck in fact when I tell people that I am having the WLS they look at me and ask where are you going to loose the weight from.. But I am over 90 lbs over weight and because of the tummy tuck you can only see the weight rolls in my back and legs mostly... If a doctor reads this can you PLEASE tell me if my tummy tuck will stay in tact as I loose the weight, or if I have wasted my money nearly 4 years ago? and Since I had my muscles done along with the tummy tuck and got a new belly button will the muscles keep my tummy from sagging? Thanks to anyone who has an answer to this....