Sooo My Boyfriend And I Have Been Together for almost 3 years . Him and his Bestfriend were like brothers . And his Bestfriend has an older sister with a kid . And when I say older..She’s almost 10 years older than me and my boyfriend. When Her brother was Deported her and my boyfriend (we weren’t even hanging out at the time ) messed around . My boyfriend told me as soon as we started dating they had a thing , which at first didn’t bother me cause it was a year or so before we even liked each other like that . But while we were dating they weren’t respecting boundaries and it was making me comfortable but he kept telling me “She’s Family, Shesl Ike my sister..it’s not like that, you’re just being jealous “ Since we started dating my boyfriend had some issues like such.and Now he finally sees how he was wrong for everything he did and how it was not appropriate or respectful to me. Soooo this morning I had a gut feeling and texted him acting like I know what he did to make him confess and said “Did you ever cheat on me ? Like in ANYFORM ... Think really hard before you answer” ....And He Tells me “Last 4th Of July....Me and ____, Almost had Sex..” I LOST MY SHIT. Cause he proved Not only were my Suspicions and Gut feeling was right AGAIN. Now Overall me and him have a Good Thing here the only issue with us is that he’s NOT UPFRONT . Now his Best-friend’s sister keeps telling me she never had or did anything with him but we both know that she’s saying that to cover her ass in case her brother found out & Keeps calling my boyfriend claim what they did never happened and how I’m a bitch . Idk if I’m gonna stay with him cause It was A year or so ago, and He’s been so much better these past months

to prove he wants and loves me . So What would you do and should I Tell His Best Friend ?