I’m seeking forgiveness regarding backbiting-what should I do?

Assalamu alaikum. I had a close friend whom I trusted with many personal matters. They ended up sharing everything with people I’m not even in touch with, maybe to stir drama (or whatever their reason was). I decided to keep my distance and unfollowed them on social media, but if I see them in public, I still greet them with salam and am polite. However, I feel guilty for pulling away suddenly without an explanation, without speaking to them first. I heard about their betrayal from another close friend, and then I cut ties. Now they act like we were never friends. Should I be the one to call and apologize, or should I just forgive them in my heart for the gossip and move on? I’m torn because I don’t want to hold grudges, but I also want to protect my peace. Edit: We were so close that they introduced me to harmful habits like vaping, and we used to do it together. I’ve since repented and quit, alhamdulillah.