RE: Converting Spaghetti Sauce to Chili
Two thoughts; My preference would be to freeze the spaghetti sauce and enjoy another day. Last resort, add about a cup, maybe two of good New Mexico Chimayo red chile powder, or Hatch green chile, a generous portion of garlic, cumin and Mexican oregano, maybe you'll be able to kill that spaghetti sauce flavor.
All in fun.
I know, be kind friends, I'm plugging New Mexico agriculture! Be honest, it's good eats!