<human>: Can you succinctly summarize the text in 1-3 sentences?

A year and a half relationship with my SO (F23) and myself M24.

*At the start of our relationship she would get text messages all the time from one guy all throughout the day, I was told this was her best friend and being that she had a lot of guy friends.
 I wasn't ok with it because I felt sometimes like I was competing with a phone but I was head over heals so I just tried to get past it. 

*A friend of mine saw this and I defended her, "it's her best friend, who am I to say shit." I told her about because I wanted total honesty, I can't stand secrets. 
 About a month into the relationship she tells me this guy who texts her all the time is her ex....I'm devastated but I had to commend her honesty and the balls it took to tell me. 

I never got over being lied to about it. 

*The texting continued and she would hang out with her friends group that they shared so he was always there. I thought I was ok with it but seeing that name come up on her phone before we would go to bed just never sat well with me. 

*Fast forward through the year and she still had never told him that she had moved on, there was the assumption that he knew through the grape vine but never did it come from her even when he called her on it. 

*My SO's best friend is her ex and I blow up periodically about it....a fight that ends up going no where but giving me the chance to vent. I get that she is with me and spends most of her time with me but I don't understand why I can't let it go to this day.
<bot>: I can't get over my SO being best friends with her ex and she has never told him we are together even when he has called her on it.