Pixie, don't give up! I'm actually in the 170s right now rather than the 270s, but when it comes down to it, we're really both on the same journey.
I CAN tell you that unless you've eaten roughly 10500 calories ABOVE your maintenance calories, you did NOT really gain it back! It's 100% water fluctuations. I've gone up or down 5+ lbs in a day with water fluctuations - don't let it get in your head.
I'm sorry to hear that it's hard for you, and I agree that was not a very understanding or sympathetic comment by the other user. Weight loss is often a hard, hard road, but it's worth it. I remember a quote that I've heard several times here:
"Being fat is hard. Maintaining your weight is hard. Losing weight is hard. Choose your hard."
Also, I wanted to say that you're always welcome to join us over at "Daily Accountability/Lifestyle Change - June 2013 - Everyone Welcome!"