Don't engage him further. He will just keep attempting to gaslight you and you may be prone to getting confused by his garbage. Write him off COMPLETELY. You don't need to explain to him "why;" he knows why, he just wants to confuse you, to twist you up inside again, so you keep putting up with his bullshit.
I agree with the gaslighting observation. Classic narcissist tactic. And I disagree with GG (and others here from time to time) that only a doctor, a psychologist, can diagnose a narcissist. First of all, their symptoms are quite clear, always the same pattern. I mean, it's really super easy to spot an entirely self centered person, once they stop pretending to care. There is tons of information on the net and in books about how to spot a narc, and how to dump one if you get tricked by them, into having a relationship. And how to heal from their inhuman shocking betrayals, the devaluation and dumping, after the idealization and love bombing.
A(sshat) love bombed you. Saying "I love you" on the first or second date was a clear red flag for me, after I'd broken up with my narc and began dating again. My narc (nicknamed Ginger in my former blog) didn't say "I love you" right away, but when I resumed dating, the next narc did say "I love you," way too soon. I'd read about this red flag when I was healing from Ginger.
Asshat is/was gaslighting you. Making you doubt conversations you had, agreements you thought you had. He wanted a "don't ask don't tell" relationship? Where you could both date others, but only when out of the country, and not tell each other about these people? But he was still fucking his exes, or sexting at least? He asked you about B, despite agreeing not to. He agonized to you while you were going to see B. He got pissy when you told him you needed space from that while traveling.
He doesn't need feelings to fuck people. Oh wait, he never fucks people unless he loves them. Back and forth. "Word salad," acting stupid about basic emotions. Saying something and shortly afterward, denying he felt it, or thought it, much less said it. Leaving your head spinning. Questioning your own memory and even your own sanity.
Triangulating you with this American woman. Triangulating you with his exes, and possible new women. Still living in your apartment because he "can't" find a place to stay. User behavior.
Even being free and easy, cool and collected, gender queer and supposedly feminist. My ex Ginger was the same way. Long flowing hair. An artist, a musician, singer and guitar player, a dancer, a pagan, supposedly worshiped goddesses, sculpted goddesses, "loved" full figured mature women... on and on. Narcs don't have a concept that other people have feelings (but they are expert at "mirroring" other people's behaviors). So they can be cool and detached, seemingly so self confident. They don't get embarrassed. They can be gender queer easily, because they don't care what others think, because to them, other people don't think or feel. Only they really exist. They have NO EMPATHY.
Like GG says, they have a black hole where a soul should be. They use others constantly for entertainment because they are empty.
By the way, you have my sympathies for living in Eastern Europe, with the sexism and homophobia. That sounds horrible. I can see why Asshat seemed attractive (at first) in contrast. And I also, sadly, see why Asshat identified you as easy prey.
As for B, I'll call him Boy, and what to do now that you're breaking up with Asshat? All I can tell you is, after 2 1/2 years with Ginger, I took a break from dating men. (I was then already in my long term relationship with my dear sweet gf for 6 years and we'd been living together 2 years, so I still had her.) I took 6 months to heal, read up on what narcissism was, how the hell this perfect man who checked all my boxes, turned out to be such a shithead, such a user, such a liar. I needed to rest. So... up to you. You've already got a LDR with Boy. But it's new. You don't need to unload all about Asshat to him. And if you do want a future good relationship with Boy, you probably want to be a whole person, a (mostly) healthy healed person. You of course, will be a better partner for any man, either Boy, or someone else, when you are calmer, more centered, more armed with knowledge of what red flags to look out for, what boundaries to keep, what kind of skepticism to have.
It must be easy to spot sexist men in your culture. How much worse is Asshat, who pretended to love you, when he is actually completely misanthropic?
Beware of a common narc behavior: they often attempt to hook you back in again after some time goes by (usually 6 weeks post break up). Once I knew it was over with Ginger, I still missed him. The old him that I thought I knew and wanted back. The great sex we'd once had. I was still friends with him on Facebook. I'd become FB friends with his latest new lovers too (a married MF couple). I was stalking them too, to see if they commented on Ginger's profile, mentioned shared experiences, feelings, things like that. I finally cut contact with all of them. I'd been messaging Ginger, since we used to text every day when we were together. it was such a part of my life.
Thanks to GG's great advice here, I cut all contact. I didn't speak to Ginger for 40 days. Oddly on day 41, he contacted me (he still had my phone number and I hadn't blocked him, just stopped talking). He wanted to reconnect. I naively wondered if we could go to FWBs. I missed our great sex. So, I did meet him! Outside, in a public park. He'd dressed up, he'd combed out his long flowing hair. He looked amazing. Too good. And he was the same old piece of shit. Leading me on, saying one thing, saying something else a bit later. Confirming, then denying. Twisting facts. All bullshit. After 90 minutes, I almost ran to my car to get the fuck away from this monster. He followed me and asked for a hug. I gave him one just because we were at that moment alone in this wooded parking lot and I was afraid of what might happen if I didn't hug him! Then that was it! Bye bye asshat.
He used to stalk my blog here when we were breaking up, and afterward. Or he had a female friend stalk it (he told me this) and tell him what I was saying. As if this somehow made him not a stalker. Narcs often engage others to do their dirty work for them. It made me paranoid to blog for a few months but finally I thought, fuck it. I'll say what I want.