So I removed the fingerg grooves on my glock 19, BUT I ****ED UP. If it's unsafe to shoot I am just going to order another lower from glockstore, but hopefully it's safe. the metal showing is the very bottom of the mag release spring.
The pic didn't show but I can't imagine that a hole in your grip is going to be more comfortable than having finger grooves.
As far as safety. The Glock frame is designed to flex during recoil. I would be concerned about a compromised frame but I can't say that your frame is unsafe based on where the damage is. The normal stress points are near the pins and the trigger guard. You could watch it carefully for hairline cracks in the grip for awhile to determine for yourself if it's safe.
If it were my gun, I personally would choose to replace the frame.
Strip the lower so that the mag spring is no longer in the pistol. Sand and de-grease the area around the hole, grab some JB Weld and patch that bad boy!
Then go forth and sin no more, meaning think twice about mods... but now you have experience in how to bugger something up, I doubt you will repeat this type of issue during further mods...
AND - If the JB Weld doesn't work, then buy that replacement frame...
We learn by doing, and you learned something - like how thin the polymer is in the grip. Life has risks, if this is the WORST you do in your life you are close to walkin on water... Know what I mean? (LOL)