Relationship and family

Today I told my stepmom that my “friend” who I’m going on vacation with next month is actually my boyfriend. It all happened so fast and I’m regretting my decision to tell her but I guess it had to come out someday. My family already knows I’m bisexual and they’re honestly not the most accepting people around. They have said pretty offensive things in the past but they know not to say it around me now since I live with them. It all came up because I told her I was going on vacation next month for my spring break. I was telling her how I secured a cheap cruise and a cheap Airbnb since I’m on a budget cause I’m a student. She was telling me how that’s nice and that it’s worth it to go. Then she asked if I was going with my friend, because she knew I went with him on my last vacation. I told her yes and then, I don’t know why it just came out, I said “he’s actually my boyfriend, but he used to be my friend.” Her response was a high pitched “mhmm” like acknowledging it and then she turned around and didn’t say anything else. It got super awkward silent so I left. I had stood there for about two minutes after finishing the dishes like I had been and then I left because I really expected her to say something else and she just didn’t. Maybe she was in shock? I don’t know. But it definitely didn't seem like the reaction I was hoping for. My mom already knows about him and she’s been supportive about it at least to my face, I don’t know what she’s said behind my back. But my dad and stepmom didn’t know at all. What sucks is that she’s met him at my last birthday party and my dad and her suspected we were more than friends. They asked my sister if she knew anything and she denied it because she knew I wasn’t ready to tell them. However they had their suspicions and my sister told me that but also said they don’t care at the end of the day. I don’t know how to feel, I guess I just felt very emotional about it because of her reaction, or lack of one. I guess it just hurts.