Men who are in committed relationships dont hold hands with their female friends, call them in the middle of the night, flirt with them openly or anything of the sort.
Your man’s friend obviously likes him. She wants him and doesnt care if she tramples over you in the process.
It really depends on your relationship spoko. If this is marriage, then I would do everything in my power to keep my relationship alive and kicking. If its just a boyfriend, then Im not sure he is worth so much effort.
To be honest, I would ignore him for a bit so I could evaluate what I want and give him a chance to miss me.