It appears you cut into the joint at the base of the fender. A picture of the fender itself would be a huge help in understanding whether you cut too deep or not. If you did, you may be looking at having someone weld up the hole or some such. That'll be a pain in the rear. Hard to tell what you "cut into" where that one pic shows the two pieces flaring away from one another. A pic of this area on the truck will tell a whole lot more.