I'm not sure if you bear any physical resemblance to your deceased brother, but if you do, that might also be an issue here.
You should certainly talk about it, and you should definitely do that while you're sober. Also, given that you are in Amsterdam by now, weed won't be a good substitute for alcohol in this case, FYI.
Sounds like you are already pretty good friends. Stuff might be awkward, but given on the dynamics you described so far, it's probably necessary to get to the bottom of this, or else either one of you might end up doing something that ruins the friendship you have.
What you should talk about? Start at what happened that night, and then see how it goes.
Good luck in any case, and make sure to enjoy your trip!