Being miserable while trying to make this big of a life change is never a good thing. Off the bat you're setting yourself up for failure.
There is a lot of great advice here. I would personally recommend a gradual decline, if you're not a cold turkey kinda person, trying to eliminate calories from your body that it's so used to getting could result you making some really bad meal decision (been there). It's a really good idea to plan a head too, I'm pretty good around the kitchen and have young kids, so where I often plan to plan my meals, that gets thrown out the window for creativity. So what I do instead is read every label on ever package of food, use things like calorie counter/myfitnesspal to determine average calorie counts per portion and go from there. I've also introduced a lot of fruit and vegetables into the house and make sure that I am getting my full serving of those when I can and i've found that my saving grace has been herbs and spices. The more the better.
I know this seems tough right now, but imagine where you'll be if you give yourself time. You'll be so proud of yourself and no one will ever be able to take that away from you.
Good luck and I hope that we continue to hear of your progress.

