My boyfriend of 18 months dated another girl for a few months up until a couple of months before we met - they stopped seeing each other because of the long summer holiday after first year of uni - she ended it. He was keen to remain friends - the reason he gave for this when he told me about this 6 months ago is that his last breakup was very acrimonious. They didn't know each other beforehand - I think they met on Tinder. I met my boyfriend in the first week of university and we've been going out since.
They started hanging out as friends alone from time to time from the start of the year. We became official, and she started dating one of his friends. He introduced us at a party a few months in, but never told me during all of their hanging out or when talking about her that they had previously dated. He was keen for us to meet each other at the party - we haven't met since. One weird thing happened one night when I was hanging out with him and his friends where he called me by her name - they sound similarish and I didn't think too much of it at the time, only recalled it later.
Nearly a year into our relationship, we were having a bit of a heart to heart with me telling him about my past sexual experiences, which amount to a couple of non-consensual experiences, one quite violent. I’d told him a bit about this before, but not in detail. He then told me that he and the girl had previously dated, and that he hadn’t wanted to tell me because he knew it would upset me (I’d been quite upset about having to have the picture in my mind when he told me about a specific quite pornographic sexual thing he’d done with acrimonious ex, and when he told me about a girl in my college with whom he’d had a one-night-stand before I came to uni).
Anyway, that was just before she went on her year abroad, so neither of us were going to see her again for the next year. I told him that while I found the thought gross and would be uncomfortable around her, I was glad he’d told me.
Yesterday afternoon, I texted him asking him how his day was going, and he casually mentioned that she was back and he’d got lunch with her. I responded expressing my discomfort, and he then replied a few hours later with confusion, before I further explained. He said “Ik ik” when I said I was upset and then stopped the conversation and went to bed, leaving me really cross and upset and unable to sleep. I texted him a bit more explaining why I was upset, and then when he eventually responded just now he just ignored that and asked how I am.
Am I being unreasonable to be upset about this? They haven’t hung out before with me knowing about their past, and my bf knew this would upset me but is refusing to engage in discussing it.