I put the sick side to the sun, like Maylay_UwU suggested and I tore out the dead part, and it seems alright now!!! :D
Oh and if you want to know what plant it is, it's crassula (in polish it's grubosz, sorry if the translation is wrong) and the subspecies is Hobbit! (or Gollum like some people call it)
Alright, gotta go to school!
Have a great timezone! :D