Search Results: cheating boyfriend another chance

Okay so I like this guy named Zack and I have a "so called" friend named Makayla well I have liked Zack for two years, and I really like him. He is also my best guy friend and we were "talking" for a while but Makayla who thinks he is cute. And well she decides to move in and starts "talking" to him. And now she likes him. And she knows I really like him. She has liked him before but she told me she stopped. I guess she didn't... but I don't really like her that much I mean she has sort of turned into a slut. She apparently liked Tate while she was dating Shawn. And she had another boyfriend this year Evan who she cheated on by making out with a guy that was 2 years older than her. And she also dated another guy. And my school has a strict policy against PDA and she actually pushed Shawn up against a wall while they were dating and started making out with him and they got in trouble and they said I love you on the first day they started dating. I mean I have always been there but she has just irritated me so I am frustrated! And I want to tell Zack how she is, because she doesn't know what she has done to guys and how she is sort of a player. And I feel like he deserves to know. Before he decides on whether he likes her or not because he doesn't know if he does or not. And I don't want to see him get hurt by her because she might cheat on him or something I wouldn't do it to sabotage their chances, even though I like him, I just want him to be happy. Should I tell him?

So in the long run, which would make you look back with the least regrets, either glad that you broke up, or remembering the relationship fondly?
Past experience welcome. Also, if anyone has good break up stories, or another reason please share :)

On a personal note (and feel free to ignore this paragraph), my boyfriend and I are breaking up when he leaves the country to go back home next week (been dating a few months). I am glad that I have a chance to say goodbye properly, and savour the moments because I know they'll be our last. But also it's harder, because there's NO reason for me dislike him, or hate him, it's just that we can't be together anymore. At least if he cheated or our personalities clashed, there's closure and I can say "we just didn't work". Also the fact that I will probably NEVER see him again is hard, whereas with a normal breakup there's a chance for drunken hookups, running in to each other on the street, drunk texting, like I would know he was THERE etc. So I'm not sure if this way of breaking up is better or worse, but I'd like to know what kind of hurt I'm in for..