Only read the first few posts so far, but wanted to post to say that I get it, and could also use some support.
I've been big most of my life (I'm 40), and hit almost 19st at my biggest and I'm only 5'3".
At that point (6 years ago), after being told I'd probably be dead in the next few years
, I managed to get down to 10st 12lbs over the course of the next 18 months or so.
I saw a dietician for a year of that and she was very helpful, but said I'd ruined my metabolism with dangerous diets.
My weightloss and change of attitude was kick started by the doctor's warning and then being really ill following one such fad diet, and I couldn't eat without being sick and was in pain for several months, which gave me those all important results on the scales; and more importantly, it shrank my stomach so that I couldn't eat very much. That combined with working with the dietician (and that magical switch in my head, which for a change, was on the right side) led to great success.
I have a lot of excess skin left, which I've found very hard to deal with and I think that's part of reason for the weight gain (subconsciously) because I still feel fat and I hate the way I look without clothes.
For about 2 years, I didn't really have any trouble keeping it off, or refusing all these lovely foods (it didn't bother me at all and I didn't feel like I was missing out); I think I liked how I looked more ( in clothes anyway), and I enjoyed the compliments.
My partner is large himself and he's a feeder. He's always buying me stuff he knows I shouldn't have and I'm finding it harder to refuse. They do say misery loves company!
I'm also a big emotional eater (boredom, stress, anger, you name it, lol) with the first 2 being the main ones.
Over the last year and a half, I've put on 2 stone, and I can't seem to shift it. I'll lose 3-5 lbs, but then it slips back on.
My willpower and drive seems to have deserted me and I'm really scared I'm going to end up at 19st again. I know I'm eating too much crap (biscuits and crisps), but I can't seem to stop.
Any help appreciated. 
OP, sorry that I don't have much advice for you.