So I'm a girl, and I'm bisexual. I'm best friends with a lesbian I'll refer to as T from now on. We've been friends since we were in pre school and we've always been there for each other. I would say T is like my sister except when we were younger (15ish so about 5 years ago now) we briefly tried going on a date but we agreed we were better as friends. We did kiss but that was as far as it ever went.
3 years ago I met a guy I'll call B, and I told him from the start that I had a (sort of) history with T and was open about my bisexuality. I'm pretty sure I actually referred to T as my ex girlfriend when I introduced them. B and I were friends for 2 years and a bit over a year ago, we started dating.
My friend group has existed for about a decade, and included T since the beginning, and B has joined it in the last 3 years. We're all very touchy-feely, and it's not weird to see any combination of the 7 of us (including T and I) hugging or play fighting or sharing a seat.
T and I were just messing about yesterday: it was warm so the entire friend group went to the beach, T made a joke about my swimsuit and I tried to dunk her so she splashed me, then one of our friends, K, made a joke along the lines of "get a room, you two".
B has rarely gotten jealous in the year we've been together. He's had his moments but they've been few and far between, and only when it was something ridiculous like one guy who hit on me right in front of him and another guy who groped me at a concert. However, something about K's comment upset him and for the hour or so we were there after that B was acting moody and wouldn't stop touching me - pulling me onto his lap or putting an arm around me. I didn't dislike it, but PDA isn't really B's thing and it was very unusual for him, which is why I picked up on it.
When we left he seemed mad at me, and when I asked if I'd done something he kind of scoffed and kept walking, and after I pressed him on it he said that he didn't like how close me and T were.
I told him that T and I would never date. We tried, we quit halfway through the first date, we are perfectly fine just being friends. I swore he had nothing to worry about.
B feels that T and I should have cut contact 5 years ago when we failed to date, and should think more about the way we interact considering the fact that we did date at one point in time and T is currently single. He thinks she might have feelings for me that go beyond friendship and because of this isn't comfortable with us maintaining a relationship while I also have a relationship with him.
I feel that since T is my oldest and closest friend and we agreed halfway through our only "date" that we wouldn't work as a couple, the half date and kiss 5 years ago shouldn't affect our friendship today, and we're not acting any differently today to how we acted before the "date". I also told B that while I respected his want for boundaries, I wasn't comfortable completely withdrawing from T the way he seemed to want me to.
I'll admit that I'm also (probably overly) cautious about my partner questioning my friendships, as the guy I dated before B told me he didn't like any of my friends and tried to convince me to cut contact with them completely. When I did, he began to abuse me regularly, and I no longer had my friends to turn to. It wasn't until I left him that I saw my friends again, so while I realise I'm probably projecting my ex onto B, I am still overly defensive of my entire friend group due to this past abuse, and struggle with partners questioning our closeness.
B is still mad at me and hasn't spoken to me since we got back, like 8 hours ago. I love him and I don't want to upset him but T is my best friend and I don't feel comfortable withdrawing from her.
Am I in the wrong here?
TL;DR: I kissed my best friend and went on a date with her 5 years ago. My BF of 1 year is uncomfortable with our close friendship. I'm uncomfortable with him being uncomfortable.