Replace it. It's junk.

No, you shouldn’t use it.

Cast iron is tough, but a crack is a crack. A hairline near the handle is especially bad because that’s where a lot of leverage and stress happen when you lift the pan. That tiny line will grow every time you heat and cool it, or if you drop it. Eventually, it will break clean off, and you’ll be holding a handle with a hot pan on the floor. Or worse, you’ll get a piece of cast iron in your food.

Some people will tell you to weld it or keep using it “carefully.” Don’t listen. Cast iron is cheap—a new Lodge is like $25. A cracked pan is not worth the burned hand, the ruined meal, or a trip to the ER. Toss it and buy a new one.

Future you deserves a handle that stays attached.