What kind of legal action can they take or might they try to take against us when we go after those clients?

Hello, I worked for a Point of Sale company for several years then left them and started my own company. They did not have me locked in with a confidentiality clause. Anyways they have and did threaten legal action when I left but never followed through. We are doing pretty good but are closing the current company to open a new one mostly for name reasons, we did not really expect to grow and succeed as well as we have and want to have a good recognizable name to grow with. At that point, all ties to the existing one will be severed and they might think we just went under. They have listed all their clients on facebook including contact information and links. We plan to visit those restaurants and try to covert them over to our software or just support them. We don’t have any client lists from when I worked there and will only be pursuing clients that come off their site that they have liked on facebook. If they can get me, what will they get me for or what would you go after me for it you were their lawyer? Do you advise we go after these sites or is it too risky? Thanks for your time and advice.