84lbs to lose. Yep, I'm going to need help.

Afternoon folks!
Long story short, I'm 5'10 and 217lbs. I've gradually put on about 56lbs in the last 15 months, probably due to the following:
1. Relationship weight. My boyfriend is a fan of huge portions, cakes, and huge portions of cake. For example, if I buy a packet of Oreos, he will devour the entire packet. As such, he tends to nag me into eating big portions and stuffing my face with dessert. Obviously, I could have just said no, so blaming him entirely would be unfair, but it didn't exactly help. It was mostly a case of him feeling self-conscious about how much he ate, so trying to make it less obvious by ensuring I ate a lot too.
2. I worked at a certain well-known fast food chain for a few months. You got given one free meal per shift, and, as much as I meant to make healthier sandwiches to bring in with me, I ended up constantly doing double shifts, meaning two meals there per day. I recently worked out just how many calories and how much fat and salt the food there contains, and it's alarming, even for someone who used to actually work there.
3. I eventually lost my job at the fast food place for "not smiling genuinely enough" (read: they were understaffed and needed a good reason to get rid of a few people). Feeling like an utter failure for losing a job which a trained chimp could do, on top of eating fatty food all the time, I also started drinking a ridiculous amount of vodka every night (at least a 70cl bottle), and mixing it with incredibly sugary, high-calorie energy drink. I worked out at one point that I was getting through nearly 2000 calories just from the booze/energy drink combination.
4. I'm extremely lazy and gluttonous and have no willpower. Actually, I probably could have skipped all the other reasons and just written this one.

Anyway, two things really made it hit home how much weight I'd gained; I visited my parents earlier this year and spent the entire time being told off about my weight. And then I tried to buy a new pair of jeans, and couldn't even fit into a UK size 20.
So now I've made changes; I avoid fatty food now, and, while I have a couple of drinks at the weekend, I leave it at that. I've switched to skimmed milk in my tea or coffee, and, when thirsty, just drink ice cold water most of the time. I fill up on vegetables, limit carbs (no more sessions in which I eat my considerable body weight in toast), leave desserts, and have become a lot more active; I power walk everywhere, do several sets of sit ups throughout the day to firm up my stomach for when the fat does eventually reduce, and am taking up roller derby. Obviously, I've only kept this up for a week so far, so it'll take a while for me to really feel/see any benefits, but, in order to keep myself motivated, I've told everyone I know about my weight loss efforts (so I'm less likely to cheat). And, obviously, I've joined this place. So.... hi! Tips and such are greatly appreciated.