You did absolutely nothing wrong imo, and yes you have a right ot be a little angry. One of the most unprofessional dives I've ever been on was in Hawaii, (I forgot where we were exactly but its was an overhead environment (lots of lava tubes and stuff), and the dm openly bragged about how he wasnt even certified or just had his sea card and thats it or some crap that wasnt funny at all.
I had the exact same situation in hawaii as well except the roles were slightly reversed. My buddy wasnt feeling well so I grabbed an insta-buddy. If I cant dive with my normal buddy I always prefer my 30cf slung under my arm but so be it.
I made to get all the info from the dm and actually sit there and plan the dive wiht my buddy (actually used it as an excuse for him to practice with a table) He did the right thing and was straight up about being a fairly new diver.
That was basically all he had to let me know and then I felt like the rest of the responsibility was on me, since there was very little guidance on the dive. I made sure to go over basic hand signals, especially safety stop 3 minutes, ascend vs. ok and to agree on how to tell each other how much air we had. Right before we got into the water the dm announced that anybody who wanted to enter the tubes could and that he didnt care. It wasnt my call but that did not sound cool to me, I asked my buddy what he wanted to do and that I would join him, he opted to follow above the first two and we did the last two toghether.
the DM also mentioned the dumb little trick that you dealt with, instead of staying toghether doing a safety stop and navigating back towards the boat, he said once you hit 500 motion to ascend and the other buddy would wave you goodbye.
That would of been the appropriate signal if you guys were able to go over it ahead of time. also no one should ever use thumbs up and ok interchangably thats jsut poor diving.
anyway everythign worked out, but ya that was the only time I've ever seen that wave your buddy goodbye and then pray tha tyou find the boat kinda dive before....