Don't try to learn everything in one day! These birds are hard to properly care for but if you took one in from some bad situation, the bird will love the chance to quietly, or not so quietly adapt. They will appreciate you not trying to change their diet overnight, a crappy diet is not going to kill a bird in a month! They will appreciate sitting in their old crappy cage and getting the feel of things, watching you and this odd new flock until they feel some semblance of safety. Their world, even if crappy, has been turned upside down.
It's true that your life has probably been turned upside down as well and that's where the rubber meets the road. Do you have what it takes? Not many people do but it is possible to calm down and BEGIN to accept what the relationship with a cockatoo can offer. Things improve over time and especially with calming tensions. These flock, prey animals recognize your fear and indecision before you do so relax.
You WILL NOT FIND the kind of help available here anywhere else. Try to read some every day and give us your feedback so it will help others. Things get better, but not overnight. I love to read the happy and proud announcements of one year anniversaries that describe a cockatoo that eats with it's flock, plays with it's flock, has learned new tricks and behaviors, goes to bed at sunset and has become a great companion. It can work for you too but please try to control your words to the staff here that only want to help. Their time is so valuable and they give it freely. Appreciate that!