Broke Chunk off Transmission How do I mend it(

I just broke off a piece of my transmission. Tightening a bolt that has what looks like a screw on the other side. Breaks on bottom of transmission right above cross member towards rear. I was rushing because at walmart and I got impatient.
Do you think i can just mend this? What product do you suggest?

I already have driven without this bolt (before I broke the chunk off, not very far though)

No way of mending that short of welding.

Does that bolt have anything to do with the starter motor?