how to get an ENFP to STFU: take them somewhere FUN!
mind you they might still want to talk later but that will shut them up for the time being.
i would explain it to him simply like you did here. that you have a hard time handling his emotional flow and emphasize that it is hurting you. unfortunately, if he keeps coming to you, my guess is that he really doesn't have anyone else that he feels good about talking to. if you are still willing to be there for him, but to a lesser degree, perhaps you could ask him to write out all his feelings and analyze them and then go through them with you every once in a while - maybe make a limit like 20 minutes talking about his issues, twice a week. it'll force him to condense to what is most important, and if he has to analyze it before he talks to you, then the emotion should be calmed down a LOT.
by the way, if he's going over the past again and again, and getting super emotional about it, that's not good... it's like ENFP depressive shit. and Fi-Si looping. if that's the case, he needs less talking and more Ne-Te stimulation. like taking up a new sport or hobby or something. it'd help a lot.
spanish culture is ESFP, imo