How to tell friend attending my wedding that i can’t attend theirs?

A couple months after my fiancé and I got engaged,
my friend announced that he and his fiancé are engaged. I’m so excited for them both! His fiancé wasn’t able to attend our engagement party because he was working, but I told my friend I couldn’t wait to meet him. His mom made a comment at our engagement party asking if I was flying back to CA for their engagement party... I never got the email invite. So, unfortunately I had not planned for that travel and didn’t go.

Fast-forward a couple months later and we received their wedding invitations in January... for a wedding in Mexico! It looks beautiful and totally up my friends alley. However, my fiancé is on a strict visa and cannot leave the country without specific consent from his country’s embassy. Not only would I feel bad going without him, my fiancé doesn’t feel comfortable with my traveling to Mexico alone without him, given recent travel news there. (He’s a sweet protective one 😜) not to mention, I’m taking a LOT of time off work for our wedding and honeymoon, and it’s not looking promising that I will have enough hours to take off if travel weren’t an issue.

So, I likely won’t be able to go it looks like. Here is the kicker — they have already RSVP’d that they are both coming to our wedding just 1 month before theirs. I feel horrible! Anyone have advice on how to let him down easy? I hate feeling so guilty. One of my friends mentioned that’s the risk they run in having a destination wedding out of the country, but it doesn’t feel any less crappy having to say no!