the event horizon around black holes is an imaginary line, far from the black hole itself, thus virtual particle pairs appearing at the event horizon cannot be converted into real particles by taking energy from the mass of the black hole. furthermore, at the event horizon the virtual particle pairs can be converted into real particles both ways — outside and inside. as the extra energy needed to convert virtual particle pairs into real particles cannot be taken from the mass of the black hole, then it is taken from the gravitational field by slowing the rotational velocity of the black hole, both for the particles outside and inside the event horizon. because of stronger gravitational pull inside the event horizon, the virtual particles should become real particles more often inside the event horizon, and to increase the mass of the black hole after falling into it. in any case, the mass of the black hole, which is far from the event horizon, cannot be affected instantly, but the creation of real particles is possible. also those real particles, which are created outside the event horizon, will ultimately fall into black hole due to its gravitational pull. the hawking radiation created at the event horizon, must be going both ways, away from black hole and in the direction of black hole. black hole cannot evaporate — the mass of black hole can only increase, even if part of the radiation is measured coming from the black hole event horizon. the extra energy, for any radiation created at the event horizon to escape, to be visible or measured outside, will come from the gravitational field by slowing the rotation of the black hole.
please don’t take the logic described above as a verified conclusion, because i came to it by visualizing the processes in my mind, without any calculations.