Whether the bolt is broken or not, I think you have to cut stuff. I fitted a hacksaw blade fitted into a crude wooden 'handle' to get into the tight spaces. (The driver's side is worse for that.) It was slow going, but it worked. I'm not sure my wrist has gotten over it yet.
In my case, the bolt was rusted into the sleeve inside the bushing. I had to cut through the sleeve & bolt at the top and bottom of the bushing. With that, the control arm came out. I couldn't 'pop' the cage off (lots of ppl say you can), so I had to cut that. Then I used a punch to get the top of the bolt (and the nut) out. All downhill from there.
FYI, I bought replacement bolts from the dealer. For the nut, after reading around, it looked the proper choice was a Class 10 'Flange Prevailing Torque lock nuts'. (M14-2.0)
I hope I never have to do it again.