Aftermath with (now) ex’s kink?

TW for NSFW and generally poor kink negotiation.

It’s been a while since I (22M) broke up with this guy (23M), but a super sweet enby I’m currently sort of dating sort of just friends with and I were ranting to each other about annoying things our exes have done and she seemed more concerned about this than me, so I wanted to get some more opinions besides hers but feel weird asking friends so I’m here, though I have heard this sub can jump to assuming the worst so please give me and my ex the benefit of the doubt here.

So my ex was into rougher sex and some borderline BDSM things, and while it’s not my kink personally for the most part I didn’t mind and enjoyed being able to make him happy. One time during he choked me and I wasn’t able to tell him it hurt because I couldn’t talk obviously, but I did try to move his hands but he didn’t seem to notice. I didn’t set this boundary at any point before and it wasn’t bad enough for me to actually pass out, and he seemed really into it, so I didn’t think too much of me being uncomfortable after. It happened several more times during the relationship, and after a couple months we broke up due to other circumstances and generally growing apart.

Is this something I should have brought up with him beforehand to avoid it, and is this common? Should I bring it up in therapy? And is it a red flag like my friend(?)/date(?) said? I have some other trauma but was fairly certain my relationships have all been okay, though this isn’t the only the ex that’s been sort of domineering with sex or in general, it’s been a pattern for the past few years so I just figured that’s how it went for everyone but is that not the case?