Yes, the first thing to do is to take a deep breath and realize that you've taken the first and possibly the most important step: Realizing that there is a problem here, and that it's time to face up to it.
Honestly, that's half the battle already won right there.
The second is to sit down and put everything down on to paper. It may not be the most pleasant way to spend an afternoon or night, but it's quite important to see what you're working with, and therefore, what your budget should look like.
When you do, please post it and I'm sure many on here can help you with ideas on what to do next.