Help needed - Busted black water pipe backing into garage

Thank you to everyone that has responded. The RV Mobile tech discovered there was a crack in the actual tank, not the pipe. It was already cracked half way around so he pulled it all the way off. Since I was paying him by the hour, I told him he could go, and I pulled the shower and black tank out myself. Below are the pictures. I must mention I cannot buy a replacement black water tank - I've tried calling the manufacturer, who just refers me to a local dealer - who says they don't sell replacement tanks for this model (yet). So I have to fix this on my own. I need to patch this black water tank, which appears to be made of fiberglass so I can attach this 3" pipe. Also if anyone knows the name of the 3" pipe and black water hose adapter please let me know so the folks at Home Depot will know what I'm talking about. Any suggestions on how I can patch this would be appreciated.