I (26F) left a hangout early because I felt out of place. Was I wrong?

I (26F) met up with a friend thinking it would just be the two of us, but when I got there she had invited another friend without telling me beforehand. I didn’t know him, and as an introvert, I was already uncomfortable.
Throughout the night, she’d leave me with him while she talked to other people. He didn’t really include me in the conversation either, so I mostly sat there awkwardly not knowing what to say. Later she went to chat with a table of pilots, and again I felt left out.
I eventually left because I felt out of place. Afterward, she called and apologized, saying she didn’t want me to feel that way and wished I’d talked to her first.
Now I feel guilty because she seemed sincere, but at the same time I didn’t know the plans involved hanging out with someone I didn’t know, and I spent most of the night feeling like an outsider.
Was I wrong for leaving, or was my reaction understandable?

TL;DR: I met up with a friend expecting a one-on-one hangout, but she had invited someone I didn’t know without telling me. She kept leaving me with him (and he didn’t really include me in the conversation), then spent time talking to another group while I felt like an outsider. I left because I felt out of place. She later apologized and said she didn’t mean to make me feel that way. Was I wrong for leaving?