I had this girlfriend “K”. K was always breaking up with me over something or just overall being distant. She, today, told me she’s not good at showing affection and is not ready to have a boyfriend. She said she would like to be good friends with me, though. :)

Idk man, sounds toxic.
I think you can be friends with an ex again, but it really depends on the circumstances and I think some time needs to pass where you need to not see each other before you can attempt to build a friendship.
6-18 months.
Just my feeling
This was my experience, yeah. It’s possible but one should be totally disconnected for a time first.