You need to increase use of the rear brake and decrease use of the front for more of a 60f/40r split regarding lever force. Applying all the force to the front is going to give you the somersault treatment easy. You may also consider giving slightly more cable slack and opening your caliper a bit more to increase braking modulation (control) at the slight expense of braking power. Having the calipers very close to the rim makes locking up the front wheel easy. Increasing that distance makes applying braking force more of a linear transition as you ramp up the lever force.