Because you did not state what the dispute is about, I cannot tell you whether to sue or not. However, generally speaking, its better not to sue. It is alway better to resolve the dispute out of court. Suing someone or being sued is very costly and emotionally draining. Rather than get your emotions up, I would recommend to evaluate your case base on how much money you will lose or gain by settling as versus suing. If you cannot settle it, go ahead and sue first.