About the social eating, I've definitely been there. Most of my life, actually. The first few weeks at my new job, people would invite me to eat with them, and I'd always do the "oh, I just ate, but I'd be happy to hang out for a bit" thing and sit with them while they ate. It's only the last week or so I can actually eat in front of them, and even then, it depends on what it is. I had roast beef, creamed cheese, and dill pickle rollups today, and couldn't for the life of me eat that in front of anyone.
The truth of the matter is, at least for these guys, they don't care what I eat, except to occasionally note that my meals are better than theirs

One time one of them commented that my WOE would kill me, and I just pointed out that he just polished off some huge double cheeseburger thing from Wendy's, a large fry, and regular soda, and that he should spend more time worrying his diet was killing him than worrying over my poor little cup of shrimp sauteed in butter and garlic. He hasn't commented since.
As others have said, I don't think at your height you are fat at 150 pounds, although I know you feel that way. When they're around, are they always in/near the kitchen? Maybe plan times to cook when they're just not around. Or stock up on things like salad ingredients and precooked chicken strips so you can make a quick salad (w/some bleu cheese dressing on it, even) and leave with it?
I promise you, even though I know it doesn't feel that way, you are worrying much more about what you put into your mouth than they are. Even if they do think any of the things you worry about (and if they do, they're no friends of yours), you know what the best revenge is, right? Lose the weight you want to lose, and love the skin you're in. That always shuts people up, at least in my experience
