You don't have to love them, but you should think they are honest and moral and have integrity. Want to know you're with a good person. Look to the people he or she thinks are good people. A good relationship is galvanizing, not in the oh-my-god-I-met-this-amazing-person-I'd-better-hurry-up-and-fix-myself sense thought there's probably a little of that when you first start seeing anyone amazing but in the way that knowing someone else believes in you makes you believe in yourself that much more.
You want to prove yourself worthy of his or her confidence. You know you can't hide your flaws for long, so you don't try.
Nor do I think you should throw away friendships willy-nilly, especially not for the sake of some fling putting his willy in your nilly. In other words, casual sex is never worth throwing away an important friendship.
But in your case, I'd say it's pretty cut and dry. A considerable amount of time has passed, your friendship with the girl has "dwindled," and the ex in question is someone you're now calling your boyfriend.
You're far past the point where you can try to simply ignore the situation and hope it goes away.best free dating sites for over 40