What you really want is for her to come back to you on your own terms.

Just a quick note.  Here is a link by Andy in which he will confirm all of your suspicions & tell you to just walk away. I said, “The best relationship is no relationship at all.”  In which during his broadcast he called me an idiot.  Not the 1st time. No doubt, he’s right. Aren’t we all? So, I wrote him back privately and jokingly saying, “Your advice on relationships is just awful, just the kind of advice I’d expect from a rich fat guy.” Anyway, what I don’t believe he is taking into consideration is that you both have freewill.  That means you can both make decisions.  I found that just telling someone.  I don’t like you.  Leave me alone or I just want to be friends.  Doesn’t work.  You see, telling you she is sleeping around just to have a baby.  Says, 2 things to me.  1st. She isn’t using protection so if you did get involved with her and she got pregnant.  It’s highly unlikely it would be yours.  2nd.  She’s looking for the knight in shining armor that cares about himself enough to just say “NO.”  I also know you don’t want to say no.  But, after that many guys, who knows what she has?  Right?  So, the ideal situation is to get her to walk away from you.  Most relationships fail because there is zero communication and because the powers to be have conspired for over a millennium to destroy all relationships.   The list of ways they have conspired to do that is too numerous to mention here, but the most obvious is having both parties in a relationship working.  Anyway, the final outcome of their efforts is the women are loose and confused about what they want and men are perceived as gimps and women are perceived as a narcissist or vice versa.   The truth is you are both a little boy and a little girl who is broken and she is crying for help from the only place she could possibly find it.  Whether she understands that or not.  So, since you have already made the decision to break it off from her, this is what I suggest.  Tell her why.  In no uncertain terms and don’t leave anything out.  She’ll get mad.  Really mad and leave.  That’s what you wanted, right?  Well, not really.  What you really want is for her to come back to you on your own terms.  Right?  Or not at all, right?  Well, guess what.  She doesn’t have any friends.  If she had any friends she wouldn’t be sleeping around trying to find one.  So, eventually, she’ll realize that you are the only one who has ever been truly honest with her and when she wants to know the truth about anything.  You are the only one she can turn too.   Baby steps.  But, never forget. It’s your honesty that brought her back and it’s that same honesty that will keep her coming back. Love is not sex, sometimes you have to choose. 2 hours in.
https://www.youtube.com/watch?v=_RpQ3ZdUSUs