I certainly wouldn't use that cap. The crack is only going to grow until it's all the way through, at which time it will crack the bearing and trash the crankshaft.
I wouldn't trust welding it either. That could warp the whole cap slightly, then it just won't fit right. Might bolt on, but doubt the bearing would be perfectly square.
I'd start making calls to CnC shops or looking for a used engine you can scavenge from.
'09 JK Rubicon
'01 XJ Sport