Re: what happens to you when you get leukemia?
nobody can answer that question.
leukemia is a complex disease because it is in the blood. your friend will most likely undergo chemotherapy treatment, amongst lots of other tests, perhaps even blood tranfusions, and if necessary probably bone marrow transplant.
please know that your friend has a battle ahead of him, depending on his medical health and how the treatments work and assuming there are no major complications along the way, there is always a chance of survival.
be there for your friend, be positive and strong and don't focus on the worst unless the medical team tell you otherwise. go ahead and be there for your friend, this is the time where he will need your support more than ever.