Confused about his post-breakup behavior

Hello.
My ex boyfriend broke up with me on November 2nd after 2 years of long distance relationship. 3 Months before the breakup, I would see that his behavior towards me had changed (e.g neglecting me more and more). I would tell him my concerns and he would say that everything was fine. I had noticed that he had gained an interest in the girl in his friends group, but he would tell me that I had nothing to worry about, that he liked her but he saw her as a friend and that I was ruining our relationship with my concerns.

The situation worsened and I told him it was better for us to have a week break. He told me that he would think about a solution to my problem, but that he didnt want to break up with me. After a week, he broke up with me telling me that “I thought about it and you were right. I had lost interest in you. The girl is not the reason. I still love you and want you as a friend”. I told him that i needed time and he said that he respected me. He now waits till i feel better and contact him.

Turns out he lied. He emotionally cheated on me. They now are getting even closer since she broke up with her boyfriend a few days ago.

I immediately went no contact after the breakup and he knew that i was pretty devastated. Logged off social media.
Then:
-He private called me a few days after.
-After days again he reached out to my brother asking him if im okay and that he will wait for me till i get over it and become friends. He told him not to tell me that he reached out. My brother said that im fine. He then ghosted him.
-He private called me in December, a day before my bday
-He private called me on my bday. I answered this time and noone was talking.
-Started reading messages from our mutual group chat on messenger. He had stopped checking the group months ago. (my brother showed me from his phone)
-He reached out to my brother again, 2 days ago. He basically said the same things but added that i am the “most beautiful, sweetest, smartest girl he has ever met” and that he will wait for me so that we talk daily again as friends. He dissapeared again.
I later see him secretly in an insta story hanging out with her.

Im utterly confused about his behavior. I dont know what to think anymore. Id like some help. Thanks in advance!