Did you talk to the DM about it afterward?? If so how did it finish up?
I mentioned it to the DM (because I still had one more dive that day and did not want it to happen again), but I didn't really discuss it with him, if that makes sense as a distinction. Thinking back, it was a combination of a few things. 1) Like you, I felt self-conscious because there was a group of other divers aboard (people I didn't know who were also diving that day) and also the DM was busy doing his thing (he was also the boat captain). 2) I worried about potentially embarrassing my dive buddy (who was sort of zen) by making a big deal. 3) I really couldn't see the point, in a way. I mean, I
had discussed with the DM ahead of time how I was new, it was my first post-cert dive, my first boat dive, and that we were going to wait until everyone else was in, so we would not feel rushed, and then he rushed me anyway. While I am all for discussion and constructive criticism, at that point I just figured if I went diving again it would be with someone else (not saying that is how I would always handle it, but that was my mood that day).
That said, my buddy and I DID discuss it, and he empathized. And we did make the second dive, which went better. I actually got off the anchor line, got all the way to the bottom, and swam around. But it left a bad taste and we cancelled our dives for the next day and then I didn't dive again for years. When I did finally dive again, I took some pains to set up the situation so that it would be more likely to be conducive to me having fun (and it worked!

) I should mention that another factor in this was ill-fitting gear, which problem I solved by doing some brainstorming here on SB, and then trying some alternatives.
Thanks for sharing your story. For me, verbally hashing it out with my dive buddy on the boat in front of all the other divers felt public & intimidating & so I didn't say a word. I was overwhelmed enough with getting thru my first dive let alone confronting him about his actions. I wanted to say something, but no words would come. I swallowed them down & resolved never, ever to dive with that person again.
While that wouldn't be optimal if you wanted to continue buddying with said person, it sounds like this is someone you no longer socialize with and won't be diving with. And maybe there were more reasons for that, such as some basic incompatibility in communication styles or personality. Sure, maybe it was all "you," but on the other hand maybe for some subtle reason(s) it just wasn't someone you felt comfortable discussing things with (a good reason not to buddy up, if so). My usual dive buddy now is someone who (like me) enjoys discussing plans and re-hashing scenarios, and that makes a big difference. Especially on a "public" dive boat, where you need to be in synch and can't suddenly start hashing out the terms of your relationship from scratch. And underwater where it can be frustrating to communicate and you/buddy may need to make an extra effort. To my mind, it's like many other other critical activities where you need acknowledgment of understanding. For example, if you're out sailing, you don't just say to your mate, "Turn 20º to port" and then leave it at that and go on with what you were doing. No, you wait for the response of something like "20º to port, gotcha" from the other person.
I think that if you are motivated to try diving again, maybe a good idea would be to get together with a good, communicative, patient instructor (and perhaps include a buddy if there is someone you now want to buddy with), and try a dive where you are in control, where there is no "crowd" you need to worry about, and where you aren't wondering what the other people are going to do, what's going on, etc. Just a simple dive where you trust the people you are with and where you also feel in control. Maybe a swimming pool, or open water if there is someplace "un-difficult."
On the other hand, if you came here more because you just want to "process" the dive experience you had, but you aren't keen on diving again, that's okay too. It's just that if it were me, and I did want to dive, I would try to set things up more in my favor and have another go - just to see. You might find you just don't take to it; but you also might find things are completely different in a good situation and you do want to go on (not that you can ultimately rely on every dive being easy and simple or else; but you are just on your first dives).