An SF340 suffered a ground conflict with a CRJ that failed to yield at a taxiway intersection.

Narrative

Our initial clearance was: taxi via XX; hold short of Uniform and contact ground on 121.8; expect Runway YYL for departure. I read it back to ground and the Captain verified it with me. As we approached Uniform on XX; we were the number one aircraft; I switched to 121.8 and contacted ground who cleared us to continue on XX; cross YL (notam closed); XX 14; and Yankee to YYL. I read it back and the captain verified it again with me.Approaching Runway YL; the Captain called cleared left and I cleared right and we proceeded to cross the closed runway. I looked down for one second and after looking back up I saw a CRJ crossing in front of us from left to right. The Captain and I slammed on the brakes and came to an abrupt stop. The CRJ moved left to avoid us and their wing tip missed out nose by between 5-10 feet. They continued down YL; we never heard them say anything to ground. Ground confirmed; when we asked; that we had followed the original and correct clearance. We told them that we would need some time to take care of things so they gave us XX hold short of XX 12. We complied after reading it back and the rest of the flight went as normal.