Hi and welcome to the club no-one asked to join. The range and duration of side effects of the drugs varies hugely between people. Many people on Glivec/Gleevac/Imatinib do at least ok and a lot fairly well. Some people have such major issues with side effects that they need to change drugs, but pretty much all find a drug that works OK. Imatinib is the generic drug name which you will most often find used on here. Most of the worst side effects improve significantly in 4-6 weeks, but some (in my case cramp, some fatigue and flatulence) persisted. To give you hope I can tell you that having been on imatinib for 10 years, I am now 11 months into treatment free remission (TFR); I last took imatinib on 22 October last year, and my counts are low and stable. You will find it easier to deal with the whole thing of you learn a bit; start with the "just diagnosed" tab under "about CML" above. I'd also recommend you look at the template questions for your doctor - take them with you to your next appointment, and get the answers. If there is anything you don't understand - look it up on here or ask us.
The vast majority of CML patients will (eventually) die with it, and most after a pretty normal lifespan; very very few will die as a result of CML devloping into accelerated phase and blast crisis.