Can i be sued for collusion if i knew nothing about the situation

You have not given enough information for anyone to be able to advise you here. I suggest you schedule a consultation with a local attorney to whom you can give all the details of your situation in order to determine your rights and obligations regarding whatever you are facing.

One can always be charged with anything. Whether the charges will stick is a different story

Sure you can be sued. Anyone can sue anyone else for anything. Doesn't mean they can win. Whether they likely can in your situation is not possible to determine without a lot more information - information you SHOULD NOT post on this or any other website. Review it all with a local attorney instead where you have both privacy and privileged communication just in case there IS any merit to their claims. You do NOT want information you posted on the web to be used against you at a trial!

Whether you knew something about the situation is one thing you will be defending. Your opinion is that you did not. Your actions may lead people to believe that you did. Get a lawyer.