Gaining

What are you afraid they'll think?

You do realize its just 20 extra lbs? All that could happen already happened. You are on a fat side already. So extra 20 pounds won't make much differense IMO. And if you're tall enough - everyone barely will notice

People thought everything they could when you doubled your weight.

Personally I would've thought that you had some health or personal issues and you blimped up because of that. And that now you're struggling to keep weight under control and if you gain those lousy 20lbs - it'll look like a little setback in a "battle" of yours.

Many people who gain on purpose love when other people notice and comment. After all, it affirms that you have been successful. You have to see what works for you. You can blow it off by saying you have gained a few pounds, or you can shock them by saying you have gained 160 pounds and never felt better.

So if your gain up to this point has been unintentional, what's motivating you to gain more? Everything in this post so far indicates that gaining more weight would be the wrong decision.