I say this because there are two good stickies at the top of this forum that can help you get pointed in the right direction to loose the weight.
You are right, you are going to have to get "militant" with your diet and clean it up if you expect to loose this much weight this fast. That is one of the key elements to succeeding.
Now, personally, I think you need to look at the big picture and not just the fact that you are going to a wedding. Loosing weight, keeping it off, is part of a bigger equation. It's about being healthier and changing bad habits to improve your lifestyle.
If you only if you only strive to attain weight loss, and don't look at the whole, you will have difficulty succeeding.
Read the stickies, then if you have questions feel free to ask. There are a lot of knowledgeable people here who can help.