Absolutely fix it!
Water in the oil - 10 to 1 it's just the water pump, a common problem on F650's. Head gasket is EXTREMELY unlikely.
As for the rest - anything is fixable, abandoning the dream of a lifetime will kill you. Get you and the bike to a town, any town, find someone with some mechanical skills, and with the help of the F650 experts here, we'll get you sorted and on the road.
Figure out the problem, order the parts, put them on and go!
Remember, there's no schedule, and problems on the road are a GREAT way to meet the local people, and that's what travelling is all about.
There's loads of advice on how to order parts and get them to SA here:
Shipping Parts | Horizons Unlimited
and of course on the HUBB.
Relax, take a break and enjoy. Sounds weird I know, but with a small attitude adjustment, in a few weeks you'll understand.