Help, how to shut off an argument with my friend who is close minded?

I don't know if you have had the same experience, but in my social circle, most of my gay friends are the ones who don't believe in bisexuality, while the straight ones support it existence.

My only issue right now is with one of those said friends. I'm 33M-bi, he is 30M-g.
He is endearing as a friend, he is there when you most need someone, he is also available to hang out, to party, and etc. Summarizing, he is a good friend. The issue is that he is hard die believer that bisex doesn't exist. That since I'm currently in a relationship with another guy I'm gay and that I should use the Gay label. Truth is, I hate to use that label on me. Nothing against gay folks, is just that I had a really hard time accepting my identity that it shocks me when someone tries to deny it (just in case, I live in a country in Latam with no rights for LGBTQ+ community, so you would understand the hardships I have lived). When I was able to understand bisexuality existed, I felt relief, but every time someone call me gay, it just reminds me of the hard days I had to live as a teenager up until young adulthood.

Well, that's the issue now... he insisted that I should be labeled gay, he tries to convince other friends to call me gay, he also has this weird idea that if I'm dating a guy I should like penis (I don't, not even to give a bj), that I'm being homophobic for not using the gay label, and he goes far enough to say that Bisexuality is not really a thing, just gay people denying their sexuality.

This is becoming tiresome and I'm thinking on cut off the friendship, tbh. There are most things around it that makes me think not, as I said, he is a great friend otherwise the topic. I was also thinking of cutting him off of the topic every time he broughts it up, which is like once every month... so I don't know how to really approach it.

I would like any advice, thanks.