Idk how to feel

My bsf recently got into a relationship and I hadn’t known either until they mentioned them and I flipped out in a surprised way and they said they had already told me they were dating this person and I said they hadn’t then they showed me a screenshot of a conversation we had a couple days ago which included them saying, and I quote “I finally flirted my way into someone’s heart” and I thought they had been joking because we joke like that and that’s all they said, they hadn’t exclusively told me they were in a relationship. 

I don’t know what I’m feeling weither it be betrayal or jealousy or that fact I just feel left out. Since that day I had also found out one of my friends were dating someone and it was all so overwhelming. Also the fact I had been asked out a bit after that but rejected them because I don’t want to be in a relationship got me all confused.

I’m not a big fan of dating myself and I had thought about the possibility of dating the friend I’m talking about but I’m just not interested in them that way. Which is why I’m so conflicted about my feelings. I guess I just wish they had told me properly. Like yk “I just got in a relationship” or something like that instead of making it sound like an elaborate joke. Idek anymore