I bought a .38 snubnose (2 in barrel) two years ago, and just got around to shoot it the first time several weeks ago.

that thing really hurts! after the first 5 rounds my palm was burning, and after the sixth round I had to yell "ouch".

I know it's because the snubnose is lighter than full barrel revolvers, which causes all the energy to transfer to my palm with my meat being the only buffer. I hold the revolver the same way Jerry Miculek does, with my off-hand's thumb wrapped above the webbing of my shooting hand.

Do you have any suggestion on what to do (change of technique etc.) to get better handle of the snubnose? Because of the "fear of pain" my accuracy is way off too, shooting at a 5 yard target the holes are all over the place (like, 4 inch groups)

My dad has a S&W that's just like that: 2inch barrel .38 special revolver. While I have my own gun (4inch .357 mag revolver with 7 rounds), what I do is keep my elbows bent, use my left hand (weak) to cup the bottom of the grip, keep myself relaxed and not have a death grip, knees bent with my left leg slightly more forward, and body is leaning slightly forward. My gun is heavier than my dad's snub, but I essentially used the same technique.

If that doesn't work, I'd suggest you move down to a 9mm semi-auto. The kick is going to be lessened, as the energy of from the blast is transferred more through the gun, and not just to your arms like a revolver. Or, you could try to work out, so you have the strength to handle your weapon.

Strong hand over weak hand? Thumbs forward? Be mindful of the hammer. Also try loading 3-4 hot rounds against 2-3 spent casings?

Not really sure.

Got treed by Hellmouth, I was also going to say try leaning into it more.