Hi Janey, sorry to here of all the troubles.
You recieved alot of good advice already but here is my 2 cents: first you may want to edit or remove your address from the text of the letter that you posted above, you never know who is watching and what they might try to do with it.
Prior to your testimony/deposition you may want to write down everything you remember (date, time, witnesses, etc) of what happened prior to your injury, and everything immediately after your injury. Try to meet with your attorney before hand. Meeting with them the same day as the testimony doesn't give you alot of time to reflect on the words used to describe the events. If they don't already have a detailed account of what occured give them a copy of your written events. It will help them with your case.
They may not be as dramatic as television but they will try to have you re-explain yourself to get you to say something contrary to the previous facts that you stated so they can harp on it and try to cause doubt on your interpretation of the events.
Also I'm not aware of the type of injury that you have but please go over your public records where you mention that you use your hands (like Linked-in). If comments are fairly recent, they will try to show that you are not in that much pain since you are able to play COD4, etc.
Hope this helps and good luck.