What do I do ? HELP

Cheyenne
So my boyfriend and I took a break, we were going to try and fix things. Then all of a sudden not even a week into it. He decides that he doesn't want to do it anymore. Then I find out this weekend that he's talking to another girl since when he told me he didn't want to work it out anymore. Now excuse my language but this woman is supposed to be a friend. And I let this bitch in my house, near my son hang out with my boyfriend. And as soon as I'm gone she's weasling her way in there ? I've already told him she's not allowed around my son. But how do I fix this ? Because he's choosing a girl over our family, us, and more importantly his son. And I'm really close to making the decision that he won't be allowed to see our son if he continues to choose this girl over us.