Hey honey, shake it off, really. Take a deep breath and move ahead. The weight loss is threatening to your friend, and maybe to your boyfriend who loved you before you started losing weight too and subconsciously our close friends are threatened when we start making positive changes in ourselves because it makes them think either a) they need to change something too and maybe there's something wrong with them or b) you won't want to be around them when you've lost weight. It's totally ridiculous, but their fears aren't logical, they're just gut fears. You almost can't really even discuss it with them because it's not like they're going around saying to themselves, "gee, once Liz is skinny she'll realize I'm not good enough for her". That's a totally stupid thought, but you can't control irrational gut feelings. Just try to be the same you as always in personality and maybe drop subtle hints about how you appreciate your loved ones' support and understanding while you make changes to your health. Even if it's a stretch to call anything they're doing "support", find some little thing, ANY little compliment, any sign of encouragement, something and turn that into positive reinforcement.
As for the bad dreams, this happened to me too a long time ago when I first started losing weight. I think it's our own way of dealing with the same fears that affect our friends when we make changes in ourselves. In a way, the layer of fat insulates us from the rest of the world and you're exposing more of your true self when you don't have to hide behind your food and body image issues anymore. Excuse the excessive psychology, but I really believe that many weight problems have psychological roots.