I don't know how to tell my parents about my (19f) relationship with him (20m)

(I'm argentinian and he's american so very far) we met online and decided to start dating and taking it seriously, I feel good in our relationship and it's been nice so far so we had plans of meeting each other, I don't have my Visa yet so he decided to come here first in July, he has everything planned, already knows where he'll stay, everything, I already know I'll be in winter break from uni and I'll also ask for a license at work, the only problem is that my parents don't know anything yet.

so my parents are old people (they had me very late lol) that are very against LDRs becsuse they basically think that always end up in k1dn4pping and catfishing lol, but I also don't wanna drop the bomb when he comes and randomly say "so yeah I've been having a boyfriend all this time and he just came here so I'll stay with him for a couple weeks bye!!"

I am starting to think I should tell them I met him irl (I live in Buenos aires and it's full of tourists so it could work) but he returned to his country and I've maintained a ldr and now he's coming again.. but I am still very scared specially because it's my first relationship and never had the "hey mom I have a boyfriend" talk, any advice?