Hi Lisa, sorry to hear you are in this position of not knowing what is happening and what to do. I am no expert but would think that your dad has seen a doctor and has been given some information regarding the status of his condition and probably a choice(hopefully) of treatment that will be the next step.
Has your dad talked to you about any of this? What are his views on what is happening? Has he had scans/biopsies?
I am sure someone else will give more constructive advice on here but you have not said what else he has been offered.
Please be positive and take on board suggestions from your dads specialist together with those on this site and try not to be too downbeat as, although it makes you feel that way, it is better to take positives rather than negatives to use against this horrible illness.
I hope your mother can eventually talk things through with you and maybe you can suggest pooling your thoughts/feelings to come up with a plan to support your dad through the tough times ahead.
Keep posting updates as the more information that you give will give a greater chance of someone on here being able to help you all.
My thoughts are with you all
Chris/woody