Total over 3 years: 126k
Median Salary in Toronto: 95k
Total after 3 years: 27k
Median Salary for Canada as I couldn't get UVic numbers: 75k
So it would take you ~5 years to make back that 100k difference. Personally, I would pay my dad back the 100k and go to Osgoode, but it's up to you.
I'd like to thank you all for your replies. They really put my ego in check. I'm chiefly interested in law school because of the intellectual rigour of the training in and practice of law and want to achieve the sorts of grades that will get me into a good firm where I can do my best work.