Breach of Contract

I have a non-compete agreement with a consulting company in Michigan (We'll call it company A). I left the company last September and, have since had another consulting firm (company B) try and place me at a client (ABC Co.) of the former company A. Company A got wind of this and called me. Company A said "we're representing you at ABC Co." I said "OK" ,agreeing to be represented by company A when I went on the interview (even though the interview was set up by Company B). We then went on talking about where else company A could place me for the remainder of the conversation (good phone conversation, not argumentative at all!). Later, company B called me back and said that company A badgered ABC Co. so much that they cancelled the interview. In my frustration I went to see company A and told them that they blew the interview and, I no longer wanted to do business with them. After our meeting I recieved a letter (from company A) stating that I am in breach of my contract. I rebutted his claims and said that HE (Company A) agreed to represent me at ABC Co. and, that I would not, and have never, breach his contract. Now, I've got a "lawyer's letter" stating that company A will not proceed with "costly litigation" if I sign a letter saying that I was:
a) in breach of my contract
b) Will discontinue slanderous remarks about company A
c) abide by the contract
d) conduct all business and coorespondence with company A's lawyer.

I don't want to sign anymore documents with company A. This is how I got into this mess in the first place! Can anyone help me!?!?!?!?!?

Any thoughts would be greatly appreciated!