Christ! You`re having a bad time!
Sorry to hear of your problems.
It`s not the end of the world though. There are a few options really.
You can take the engine out and have the cracked casing welded up. Which is what I would prefer to do.
Or, you could drain the oil. Clean the area with a solvent type cleaner then rough the area up with some emery cloth/sand paper/wet and dry paper. Brush away the filings/dust and clean again with the solvent cleaner. Then seal the cracked area up with some epoxy type resin. You can get an Aluminium loaded two part resin. Devcon F or Metal set. Once it`s set you can dress up any rough looking bits with the emery paper. This can act as a temporary or permanent repair depending on how you feel.
Another option is to get another set of cases or a bottom end.
Hope you get it sorted soon.