I don’t know what to do!?!

So last summer my boyfriend and I were having financial issues, so we moved into his dads house and his friend moved in with us.. My boyfriend and I were having serious relationship issues we weren’t having sex anymore, we hardly EVER talked and had meaningful conversations.. shit we hardly said I love you... he had a serious drinking problem... and I myself had my issues with depression and self confidence. What I’m getting at is me and my boyfriends best friend got really close.. he became my favorite person and my best friend.. and I’ve never had that... the most we ever did was hold hands, talk, and we did kiss once. Jumping forward to now, I never told my boyfriend what happened and now he’s starting to hang out with his friend again and I just don’t know what to do.. my boyfriend and I have worked on some of the issues we had but nothing has really changed and his friend coming back into my life just feels like a sign that we aren’t meant to be not that I want to be with his friend, even though something happened between us I could NEVER actually go through with breaking up a friendship.