fuck this job.com

Ok, as most of you know, I have been offered another job which I have taken. I start my new job on the 27th March 2006 and I have now handed in my Notice.

My Bosses, obviously were not happy about this, but relised that they have no chance of talking me into staying. We agreed that I would finish up all my current jobs and fufil all tasks that had been asked of me before I left.

One of these tasks is a Court Case for which I have to give evidence against a Client. Its a long story but to quickly summarise;

1. Client hires us. We complete job asked of us by client and issue fee account.
2. Client does not pay and after several phone calls and letters from our Accounts Department we threaten him with Court Action.
3. Client calls up using his Company Name (which we did not know) and states that an account is paid and he needs a receipt for his records. He never gives me his name just his Company name. Anyway, I check to see if it is paid, I look in both our account books, in the first one, when an account is paid we take the account out, when I checked the account was not in it. The second book has the date of which the client would have paid written against the job, when I checked I thought it said 0/5 (as it was 2005, I guessed it was the year or something?!).
4. After checking and him continuly saying the account was paid, I send him out a receipt.
5. Two days later an angry accounts bitch tells me he has not paid and that he tricked me into giving him a receipt.
6. We try to contact him, without luck.
7. We issue County Court Proceedings
8. I write out a statement (this is send to court as well)
9. Client claims to have paid using the receipt as proof
10. I am offered another job which I take
12. I hand in my notice on Friday
13. Come in this morning and am told my evil boss that no matter wht I have to go to court. I tell them that they have until the 27th of March to get the Court date sorted because I will not take any holiday for the first three months at my new job as it would look bad.
14. I am told to be very careful what I say in Court as I could be accused of theft. (The Client is claiming he paid in cash and gave it to me, as such, he could say that I stole it.)

WHAT DO I DO???

If the Judge settles in the Clients favour, I could be accused of theft! Is there anything I can do? Should I get the Police involved? Also, if I am accused, is it a good idea to then take the Client to court for Defimation of Character against me?

HELP!