Don't be scared! Get informed and then get the procedure done. You will not regret it despite the few months of rehab.
My aneurysm was diagnosed at 5.4cm last November. They told me to continue to exercise by walking... nothing else too strenuous, but it is important to stay as healthy as possible prior to surgery. I had my surgery late Feb, was in the hospital for 7 days but then went home and was walking 10-15k steps daily within 3 weeks. Despite one setback, I am back to walking, hiking and biking like I was before surgery.

As the others have said, you do want to find a surgeon who does this surgery regularly. It is worth researching... there are a lot of good ones out there.