ive had the same mistake on my DC last year.
what i did, i removed the top cover so it does not rub on the camgears anymore.

about the loose belt, make sure that everything is lined up 1 @tdc crank lined up with the lower cover mark.


then with a 14mm socket, loosen (donot take out) just loosen the timing belt tensioner bolt and then just tighten it back up. your belt should be tensioned better than before.