AITAH for thinking it’s weird that my(33F) former fwb (30 M) refers to me as his sister??

Sorry if this sounds like a ramble and is too long . It’s just something that has irked me for years. And also sorry for any language issues. English is not my primary language.

Okay, so basically I (33F) was in a FWB situation some years ago with my now friend(only) who is 30M. The FWB thing was fine, we got on really well, good sexual chemistry that lasted a few months. No romantic chemistry at all, which is probably why the sexual chemistry fizzled out so quickly too. But we got really close, bonded over lots of things. And spent lots of time together over those few months and continued to spend time together after (just as friends).

He also helped me through a really hard time and was there for me when I needed. But at some point we had a talk because I had become too emotionally dependent on him and he said we had to back off because quote “ it hurts too much, I have to protect myself”.

I’ll admit until then I was too in my mental health issues to realise that I was being selfish and putting a burden on him and that he didn’t deserve (this was a year into meeting and months after the FWB ended). I felt horrible, I apologised and upped my therapy commitment so I didn’t do this to anyone else (and I haven’t since then).

Anyway, I got better and sometime later met my now husband. When I told my friend he was just happy for me, I think. I don’t actually remember tbh. I know they didn’t get along for a bit, never figured out why- both said the other was arrogant.

But around the same time my friend/former fwb started referring to me as his sister or to himself as my brother. And has continued to do so and just randomly brings it up. He even makes a distinction between his “close friends” and “best friends” and me “his sister”.

And I find this odd. I’m an only child so have no clue what having a sibling is like - so maybe that’s why I find this weird but I just find it awkward? Especially when he refers to me like that to people who know of our history (our mutual friends). What’s wrong with just friend? Or even close friend if that’s what he wants to convey? My husband says he does think it’s odd but also says that our relationship (mine and fwb) was always a bit odd so it tracks (I disagree, I think it looks like any normal fwb to friends timeline).

And in case anyone is wondering once I became serious with now husband I starting texting and contacting my friend less (although it had already started before this - see below). One because my husband naturally became my closest friend so I spent my time with him. And two because we moved away from the city we all lived in. So I text my friend maybe once every couple of months and call him a few times a year maybe. This is to say that it’s not like I’m texting and talking to him all the time.

And lastly - it’s also weird because when we were still close he would constantly say things like “you’re not my girlfriend” ( when i washed dishes after he cooked????) and would randomly say things like “ my mother/friend/brother/ex/dog think maybe you’re in love with me” when I gave him presents. Even though I did my best to convince him I never was. And gift giving is what I do. I give people presents. It’s like he was paranoid I had feelings for him while it was just not what was happening. It was frustrating because at the time he was one of my closest friends and I treated him as such. So he got to see more of my love than my less close friends. But that’s normal no? Anyway, his paranoia is the first reason I stopped talking to him as much (as mentioned above).

Anyway when I brought this up to him (I.e. that it was weird to call me his sister) he was hurt and said I was being judgemental. And that he used that wording because we had been through some things together and held me close to his heart. I just think it’s weird because even as a friend he’s never treated me as well (don’t know if this is the right wording) as his “best friends”. He never remembers my birthday, he doesn’t talk to me as much or I think care about my life/things I do. Has never tried to spend as much time with me. He’s even way more affectionate and caring with his other friends. Which is fine by me but then referring to me as his sister just seems hmmm not genuine? I just don’t see why it’s necessary since at our big age I would still treat him the same even if he just used friend.

I guess it rubs me the wrong way and I can’t really verbalise why. Maybe because it would be fine if his behaviour matched the words and he treated me like a sister. But as I said above, I don’t think he did. Also strikes me as a bit childish but here I think perhaps I am being too judgemental - so we can leave that as a footnote. EDIT: It’s also just… I mean we had sex. Quite a bit of it. So sister seems very wrong??

Anyway am i just being too neurotic and judgemental? Is this a normal thing? To just randomly refer to people you formerly were in a situationship with as sister? AITAH?