Oncology nurses, other patients and books will all be helpful. This has happened to many other people and they will all be eager to help. There are many books available describing your exact situation. Whatever the source, it will not be long before you have enough information to rationally discuss and make a plan with your doctor for what will be the next step. Once everybody understands the situation and goals have been set and a plan agreed upon, the initial fear and anxiety will subside.
Most people settle down.
They have intellectualized the problem and are proceeding in a rational manner to try to solve it. But, just because you are now dealing with the situation in an intellectually rational manner does not mean that you can avoid your irrational emotions. The emotions are still there and will always be there. Emotions are irrational. That can be detrimental, but it is also supremely beneficial.