Confidentiality and No Solicitation Agreement in CA

I worked at a company for three years as a sales rep. I signed a "confidentiality and no solicitation agreement" when I started working there along with my compensation contract, etc. After three years of working for the company, and being a top producing sales rep, I left the company and started my own limited liability company. The agreement I signed states that "I agress for a period of one year that I shall neither directly or indirectly solicit business as to products or serivies competitive with those of the company"...etc. The company is now threatening to sue me. I can give many details, but the bottom line is does this type of document hold up the court of law in CA against me? They are threatening me hard core to either come back and work for them or they will sue me. I of course do not want to work for them, especially under these circumstances. I just need to know what my rights are in CA and how to proceed to cover my back personally and professionally.