It sounds terrifying, I'm so glad you're alive to tell the tale.
I too had a near death experience, 4 years ago. Afterwards I was, as you appear to be, in shock for about a week. I just kept thinking about what had happened and thinking "Yeah, I'm OK, but what IF...?" and thinking about what would have happened if I HAD died - how my husband would have had to tell our daughters, how my parents and sister would feel. I just couldn't seem to stop thinking of the worst case scenario, even though I'd come through it and survived.
I became very anxious, I was terrified of going to sleep in case I didn't wake up and started to have panic attacks. Eventually, after about a month my GP prescribed a week of Zopiclone to get me back into a normal sleeping pattern and Propranalol to deal with the panic and anxiety (it slows your heart rate down so you can't experience the physical effects of panic so strongly, which helps the mind to take control) and I was diagnosed with PTSD.
Once the anxiety, panic and sleeping were under control, I started to feel almost euphoric at times, simply at the thought of being alive! I really did 'count my blessings' and tried to enjoy every day. This feeling lasted on and off for about a year. I'm still more grateful for my life than I was before I nearly died, but I'm on a much more even keel about it all now. The anxiety is still there on occasion and I still have the odd night where I can't sleep and keep reliving what happened, but happily, they are few and far between.
Please give yourself time. This has only just happened and of course it's going to have a massive impact on how you think, feel and act for some time to come. It would be odd if it didn't! As PPs have suggested, be kind to yourself, talk about it, visit your GP once you're home if you're having trouble sleeping or are feeling anxious or panicky and remember that the strength of these feelings will diminish over time. You made it - you're alive, and if you're lucky, you may even get the same sense of euphoria that I experienced and you'll feel doubly grateful for everything!
I hope the rest of your holiday is peaceful and uneventful!