"Who would be feeling better in the world right now? No-one," said Slingsby. "I've worked for 12 years to get there. I put everything I had into it and I've done it. I couldn't be happier."
Kontides, meanwhile, became Cyprus's first ever Olympic medallist since they first competed as an NOC in their own right at Moscow 1980.
On his achievement Kontides said, "I guess back home they are waiting for me and when I get back there it will be huge celebrations. I still didn't understand how an huge achievement this is for my country, the first ever Olympic medal but I guess when I have it over my neck and when I am back home with my compatriots then I will really understand what's going on.
"It didn't really sink in because I was trying to keep away from all this media and stuff all these days to try and keep my focus for the race and still when the medal was guaranteed I still didn't allow myself to be emotional. We still had the race for today so I had to keep my concentration."
Slingsby, 27, won gold by holding onto his lead going into the Medal Race, being 14 points ahead of the Cypriot at the start.
In 16-knot winds on the Nothe course, Slingsby match-raced Kontides from the pre-start, shadowing and blocking his Cypriot opponent for the first half of the race before sailing ahead to finish ninth, with Kontides ending up last.
"I think going to watch the Stars and the Finns yesterday was a very smart idea in the end," said Slingsby. "I saw how easily it can slip through your fingers and today I was pretty brutal, but I had to be. I knew Pavlos couldn't lose second so I didn't want to give him an inch all day."
In another race-within-a-race, Rasmus Myrgren (SWE) came from behind at the first mark to finish third after starting just one point ahead of Tonci Stipanovic (CRO). Myrgren finished sixth to finish in bronze medal position and Stipanovic trailed in eighth to come fourth overall.
However, as the boats started out on the water the equipment inspection committee issued a protest against Myrgren's boat under rules 3.2 and 3.3 relating to 'repair and replacement of boats and equipment'. A proteswas heard but Myrgren was not penalised and held on to the bronze medal position.
1. Tom Slingsby (AUS) - 43pts
2. Pavlos Kontides (CYP) - 59pts
3. Rasmus Myrgren (SWE) - 72pts
4. Tonci Stipanovic (CRO) - 77pts
5. Andrew Murdoch (NZL) - 87pts
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