It's good news that youdon't need to worr about your membranes.
I had GD with my last child. It really was no drama at all. I kept a food diary and had to do glucose levels 4 times a day. I quickly learnt what I could and couldn't eat. I lost quite a bit of weight due to the dietry changes which I have since maintained. It is unlikely that you will need to be managed with insulin (though it does happen) usually dietary changes are all that are needed.
It is upsetting when you find out something is a bit amiss but truly youwill find it very manageable I am really sure.