help with keeping holiday secret from parents?

Ok so I plan on going on a trip to Amsterdam for a few days with my boyfriend soon but i come from a pretty strict family so i've told them its a uni based trip to budapest. Thing is my mum overheard me talking about it to him over the phone but i just told her its a guy from my group. Since she's suspicious, she said she wants the phone number of a friend i'm going with and the number of the hotel im staying at. I'm more worried about the latter because if i give them the number of the actual hotel im staying at (but make sure there's a hotel of the same name in budapest), surely they'd figure out its not in budapest?

I really dont know what to do because this was supposed to be for his bday and I don't want to outright rebel against my parents because it just causes so many issues which i cba to deal with rn...