Is it normal to gossip about a friend of 12 years?

I have a friend from grade school who's been friend with me for over 12 years and we are in different colleges. We were super close in grade school and have been friends throughout middle school and high school, but haven't seen each other much after we went to college. Last winter break, we felt like we should catch up with each other's lives and I invited her to visit me in a different state for a few days. Since she felt unsafe to live in a hotel, I invited her to live in my dorm and I have an extra mattress she could sleep on.

Everything was good until the second night. I was walking back to my room from the community bathroom until suddenly I heard her talking on the phone with her friend on the other side of the hallway and my name was mentinoed. I stopped walking and heard her saying the mattress I let her sleep on was unclean becuase it was second hand. I also caught her saying it was gross that I only took two showers a week, and that it was gross to go thrift shopping. I was shocked. I couldn't believe that my friend of so many years could talk shit behind me, and it wasn't exactly behind me; it was around me when she was at my place.

I confronted her immediately after she came back from calling. She became very apologetic and uneasy, and said she didn't realize that I could hear it. I said it wasn't about whether I could hear it or not. It was about talking shit behind your friend over some petty things.

She then told me she became used to gossiping in high school because every single girl in her high school gossiped behind their friends' back. I asked her if she felt sad when she found out her friend gossipping behind her, and she said yes, but she felt better after gossiping about this person to someone else. She also told me she was bad at confrontation, so to feel better about something someone did that bothered her, she would complain about it instead of solving the issue.

I was so disappointed that someone I trusted and believed this much would talk shit behind me. I told her that I wanted to be her friend, but my bottom line was that she stops gossiping about me. She agreed.

Now several months have passed and we had fewer and fewer messages exchanged over time. I tried to catch up with her several times, but she either stopped replying after a few texts or didn't show up to our scheduled videocall. I have no clue why our relationship went downhill. Maybe she didn't think it was a big deal to gossip?